diff --git a/docs-util/fixture-gen/src/services/test-pay.js b/docs-util/fixture-gen/src/services/test-pay.js
index 481261b3a0..7f5c3a0781 100644
--- a/docs-util/fixture-gen/src/services/test-pay.js
+++ b/docs-util/fixture-gen/src/services/test-pay.js
@@ -1,10 +1,10 @@
-import { PaymentService } from "medusa-interfaces";
+import { AbstractPaymentService } from "@medusajs/medusa";
 
-class TestPayService extends PaymentService {
+class TestPayService extends AbstractPaymentService {
   static identifier = "test-pay";
 
-  constructor() {
-    super();
+  constructor(_) {
+    super(_);
   }
 
   async getStatus(paymentData) {
diff --git a/docs/content/advanced/backend/payment/how-to-create-payment-provider.md b/docs/content/advanced/backend/payment/how-to-create-payment-provider.md
index e867ffe91c..2c781c854a 100644
--- a/docs/content/advanced/backend/payment/how-to-create-payment-provider.md
+++ b/docs/content/advanced/backend/payment/how-to-create-payment-provider.md
@@ -47,9 +47,9 @@ These methods are used at different points in the Checkout flow as well as when
 The first step to create a payment provider is to create a file in `src/services` with the following content:
 
 ```jsx
-import { PaymentService } from "medusa-interfaces"
+import { AbstractPaymentService } from "@medusajs/medusa"
 
-class MyPaymentService extends PaymentService {
+class MyPaymentService extends AbstractPaymentService {
 
 }
 
diff --git a/integration-tests/api/__tests__/taxes/manual-taxes.js b/integration-tests/api/__tests__/taxes/manual-taxes.js
index 79c53033a5..89831bc9b6 100644
--- a/integration-tests/api/__tests__/taxes/manual-taxes.js
+++ b/integration-tests/api/__tests__/taxes/manual-taxes.js
@@ -6,8 +6,6 @@ const { initDb, useDb } = require("../../../helpers/use-db")
 
 const {
   simpleProductTaxRateFactory,
-  simpleShippingTaxRateFactory,
-  simpleShippingOptionFactory,
   simpleCartFactory,
   simpleRegionFactory,
   simpleProductFactory,
diff --git a/integration-tests/api/src/services/test-pay.js b/integration-tests/api/src/services/test-pay.js
index eed8aa80e5..eb202c01c2 100644
--- a/integration-tests/api/src/services/test-pay.js
+++ b/integration-tests/api/src/services/test-pay.js
@@ -1,10 +1,10 @@
-import { PaymentService } from "medusa-interfaces"
+import { AbstractPaymentService } from "@medusajs/medusa"
 
-class TestPayService extends PaymentService {
+class TestPayService extends AbstractPaymentService {
   static identifier = "test-pay"
 
-  constructor() {
-    super()
+  constructor(_) {
+    super(_)
   }
 
   async getStatus(paymentData) {
diff --git a/integration-tests/plugins/src/services/test-pay.js b/integration-tests/plugins/src/services/test-pay.js
index eed8aa80e5..eb202c01c2 100644
--- a/integration-tests/plugins/src/services/test-pay.js
+++ b/integration-tests/plugins/src/services/test-pay.js
@@ -1,10 +1,10 @@
-import { PaymentService } from "medusa-interfaces"
+import { AbstractPaymentService } from "@medusajs/medusa"
 
-class TestPayService extends PaymentService {
+class TestPayService extends AbstractPaymentService {
   static identifier = "test-pay"
 
-  constructor() {
-    super()
+  constructor(_) {
+    super(_)
   }
 
   async getStatus(paymentData) {
diff --git a/packages/medusa-interfaces/src/index.js b/packages/medusa-interfaces/src/index.js
index 10cf36af65..9cf865cf57 100644
--- a/packages/medusa-interfaces/src/index.js
+++ b/packages/medusa-interfaces/src/index.js
@@ -1,7 +1,7 @@
 export { default as BaseService } from "./base-service"
-export { default as FileService } from "./file-service"
+export { default as PaymentService } from "./payment-service"
 export { default as FulfillmentService } from "./fulfillment-service"
+export { default as FileService } from "./file-service"
 export { default as NotificationService } from "./notification-service"
 export { default as OauthService } from "./oauth-service"
-export { default as PaymentService } from "./payment-service"
 export { default as SearchService } from "./search-service"
diff --git a/packages/medusa/src/api/routes/store/carts/create-payment-sessions.ts b/packages/medusa/src/api/routes/store/carts/create-payment-sessions.ts
index 15d5a8dbac..537268ab2e 100644
--- a/packages/medusa/src/api/routes/store/carts/create-payment-sessions.ts
+++ b/packages/medusa/src/api/routes/store/carts/create-payment-sessions.ts
@@ -2,6 +2,7 @@ import { defaultStoreCartFields, defaultStoreCartRelations } from "."
 import { CartService } from "../../../../services"
 import { decorateLineItemsWithTotals } from "./decorate-line-items-with-totals"
 import { EntityManager } from "typeorm";
+import IdempotencyKeyService from "../../../../services/idempotency-key";
 
 /**
  * @oas [post] /carts/{id}/payment-sessions
@@ -26,17 +27,97 @@ export default async (req, res) => {
   const { id } = req.params
 
   const cartService: CartService = req.scope.resolve("cartService")
-
+  const idempotencyKeyService: IdempotencyKeyService = req.scope.resolve(
+    "idempotencyKeyService"
+  )
   const manager: EntityManager = req.scope.resolve("manager")
-  await manager.transaction(async (transactionManager) => {
-    return await cartService.withTransaction(transactionManager).setPaymentSessions(id)
-  })
 
-  const cart = await cartService.retrieve(id, {
-    select: defaultStoreCartFields,
-    relations: defaultStoreCartRelations,
-  })
+  const headerKey = req.get("Idempotency-Key") || ""
 
-  const data = await decorateLineItemsWithTotals(cart, req)
-  res.status(200).json({ cart: data })
+  let idempotencyKey
+  try {
+    await manager.transaction(async (transactionManager) => {
+      idempotencyKey = await idempotencyKeyService.withTransaction(transactionManager).initializeRequest(
+        headerKey,
+        req.method,
+        req.params,
+        req.path
+      )
+    })
+  } catch (error) {
+    res.status(409).send("Failed to create idempotency key")
+    return
+  }
+
+  res.setHeader("Access-Control-Expose-Headers", "Idempotency-Key")
+  res.setHeader("Idempotency-Key", idempotencyKey.idempotency_key)
+
+  try {
+    let inProgress = true
+    let err: unknown = false
+
+    while (inProgress) {
+      switch (idempotencyKey.recovery_point) {
+        case "started": {
+          await manager.transaction(async (transactionManager) => {
+            const { key, error } = await idempotencyKeyService
+              .withTransaction(transactionManager)
+              .workStage(
+                idempotencyKey.idempotency_key,
+                async (stageManager) => {
+                  await cartService.withTransaction(stageManager).setPaymentSessions(id)
+
+                  const cart = await cartService.withTransaction(stageManager).retrieve(id, {
+                    select: defaultStoreCartFields,
+                    relations: defaultStoreCartRelations,
+                  })
+
+                  const data = await decorateLineItemsWithTotals(cart, req, {
+                    force_taxes: false,
+                    transactionManager: stageManager
+                  })
+
+                  return {
+                    response_code: 200,
+                    response_body: { cart: data },
+                  }
+                })
+
+            if (error) {
+              inProgress = false
+              err = error
+            } else {
+              idempotencyKey = key
+            }
+          })
+          break
+        }
+
+        case "finished": {
+          inProgress = false
+          break
+        }
+
+        default:
+          await manager.transaction(async (transactionManager) => {
+            idempotencyKey = await idempotencyKeyService
+              .withTransaction(transactionManager)
+              .update(
+                idempotencyKey.idempotency_key,
+                {
+                  recovery_point: "finished",
+                  response_code: 500,
+                  response_body: { message: "Unknown recovery point" },
+                }
+              )
+          })
+          break
+      }
+    }
+
+    res.status(idempotencyKey.response_code).json(idempotencyKey.response_body)
+  } catch (e) {
+    console.log(e)
+    throw e
+  }
 }
diff --git a/packages/medusa/src/api/routes/store/carts/decorate-line-items-with-totals.ts b/packages/medusa/src/api/routes/store/carts/decorate-line-items-with-totals.ts
index 8707770db8..ffea29618f 100644
--- a/packages/medusa/src/api/routes/store/carts/decorate-line-items-with-totals.ts
+++ b/packages/medusa/src/api/routes/store/carts/decorate-line-items-with-totals.ts
@@ -6,17 +6,16 @@ import { EntityManager } from "typeorm";
 export const decorateLineItemsWithTotals = async (
   cart: Cart,
   req: Request,
-  options: { force_taxes: boolean } = { force_taxes: false }
+  options: { force_taxes: boolean, transactionManager?: EntityManager } = { force_taxes: false }
 ): Promise<Cart> => {
   const totalsService: TotalsService = req.scope.resolve("totalsService")
 
   if (cart.items && cart.region) {
-    const manager: EntityManager = req.scope.resolve("manager")
-    const items = await manager.transaction(async (transactionManager) => {
+    const getItems = async (manager) => {
+      const totalsServiceTx = totalsService.withTransaction(manager)
       return await Promise.all(
         cart.items.map(async (item: LineItem) => {
-          const itemTotals = await totalsService
-            .withTransaction(transactionManager)
+          const itemTotals = await totalsServiceTx
             .getLineItemTotals(item, cart, {
               include_tax: options.force_taxes || cart.region.automatic_taxes,
             })
@@ -24,7 +23,17 @@ export const decorateLineItemsWithTotals = async (
           return Object.assign(item, itemTotals)
         })
       )
-    })
+    }
+
+    let items
+    if (options.transactionManager) {
+      items = await getItems(options.transactionManager)
+    } else {
+      const manager: EntityManager = options.transactionManager ?? req.scope.resolve("manager")
+      items = await manager.transaction(async (transactionManager) => {
+        return await getItems(transactionManager)
+      })
+    }
 
     return Object.assign(cart, { items })
   }
diff --git a/packages/medusa/src/api/routes/store/carts/update-payment-session.ts b/packages/medusa/src/api/routes/store/carts/update-payment-session.ts
index 279e6512c9..67b9ca8aed 100644
--- a/packages/medusa/src/api/routes/store/carts/update-payment-session.ts
+++ b/packages/medusa/src/api/routes/store/carts/update-payment-session.ts
@@ -53,5 +53,5 @@ export default async (req, res) => {
 
 export class StorePostCartsCartPaymentSessionUpdateReq {
   @IsObject()
-  data: object
+  data: Record<string, unknown>
 }
diff --git a/packages/medusa/src/interfaces/index.ts b/packages/medusa/src/interfaces/index.ts
index b19351aeef..38c2dfccc7 100644
--- a/packages/medusa/src/interfaces/index.ts
+++ b/packages/medusa/src/interfaces/index.ts
@@ -9,3 +9,4 @@ export * from "./price-selection-strategy"
 export * from "./models/base-entity"
 export * from "./models/soft-deletable-entity"
 export * from "./search-service"
+export * from "./payment-service"
diff --git a/packages/medusa/src/interfaces/payment-service.ts b/packages/medusa/src/interfaces/payment-service.ts
new file mode 100644
index 0000000000..03a068f675
--- /dev/null
+++ b/packages/medusa/src/interfaces/payment-service.ts
@@ -0,0 +1,116 @@
+import { TransactionBaseService } from "./transaction-base-service"
+import {
+  Cart,
+  Customer,
+  Payment,
+  PaymentSession,
+  PaymentSessionStatus,
+} from "../models"
+import { PaymentService } from "medusa-interfaces"
+
+export type Data = Record<string, unknown>
+export type PaymentData = Data
+export type PaymentSessionData = Data
+
+export interface PaymentService<T extends TransactionBaseService<never>>
+  extends TransactionBaseService<T> {
+  getIdentifier(): string
+
+  getPaymentData(paymentSession: PaymentSession): Promise<PaymentData>
+
+  updatePaymentData(
+    paymentSessionData: PaymentSessionData,
+    data: Data
+  ): Promise<PaymentSessionData>
+
+  createPayment(cart: Cart): Promise<PaymentSessionData>
+
+  retrievePayment(paymentData: PaymentData): Promise<Data>
+
+  updatePayment(
+    paymentSessionData: PaymentSessionData,
+    cart: Cart
+  ): Promise<PaymentSessionData>
+
+  authorizePayment(
+    paymentSession: PaymentSession,
+    context: Data
+  ): Promise<{ data: PaymentSessionData; status: PaymentSessionStatus }>
+
+  capturePayment(payment: Payment): Promise<PaymentData>
+
+  refundPayment(payment: Payment, refundAmount: number): Promise<PaymentData>
+
+  cancelPayment(payment: Payment): Promise<PaymentData>
+
+  deletePayment(paymentSession: PaymentSession): Promise<void>
+
+  retrieveSavedMethods(customer: Customer): Promise<Data[]>
+
+  getStatus(data: Data): Promise<PaymentSessionStatus>
+}
+
+export abstract class AbstractPaymentService<
+    T extends TransactionBaseService<never>
+  >
+  extends TransactionBaseService<T>
+  implements PaymentService<T>
+{
+  protected constructor(container: unknown, config?: Record<string, unknown>) {
+    super(container, config)
+  }
+
+  protected static identifier: string
+
+  public getIdentifier(): string {
+    if (!(<typeof AbstractPaymentService>this.constructor).identifier) {
+      throw new Error('Missing static property "identifier".')
+    }
+    return (<typeof AbstractPaymentService>this.constructor).identifier
+  }
+
+  public abstract getPaymentData(
+    paymentSession: PaymentSession
+  ): Promise<PaymentData>
+
+  public abstract updatePaymentData(
+    paymentSessionData: PaymentSessionData,
+    data: Data
+  ): Promise<PaymentSessionData>
+
+  public abstract createPayment(cart: Cart): Promise<PaymentSessionData>
+
+  public abstract retrievePayment(paymentData: PaymentData): Promise<Data>
+
+  public abstract updatePayment(
+    paymentSessionData: PaymentSessionData,
+    cart: Cart
+  ): Promise<PaymentSessionData>
+
+  public abstract authorizePayment(
+    paymentSession: PaymentSession,
+    context: Data
+  ): Promise<{ data: PaymentSessionData; status: PaymentSessionStatus }>
+
+  public abstract capturePayment(payment: Payment): Promise<PaymentData>
+
+  public abstract refundPayment(
+    payment: Payment,
+    refundAmount: number
+  ): Promise<PaymentData>
+
+  public abstract cancelPayment(payment: Payment): Promise<PaymentData>
+
+  public abstract deletePayment(paymentSession: PaymentSession): Promise<void>
+
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  public retrieveSavedMethods(customer: Customer): Promise<Data[]> {
+    return Promise.resolve([])
+  }
+
+  public abstract getStatus(data: Data): Promise<PaymentSessionStatus>
+}
+
+export function isPaymentService(obj: unknown): boolean {
+  return obj instanceof AbstractPaymentService || obj instanceof PaymentService
+}
diff --git a/packages/medusa/src/loaders/defaults.ts b/packages/medusa/src/loaders/defaults.ts
index 6d4d26ea43..25324790f6 100644
--- a/packages/medusa/src/loaders/defaults.ts
+++ b/packages/medusa/src/loaders/defaults.ts
@@ -1,4 +1,8 @@
-import { BasePaymentService, BaseNotificationService, BaseFulfillmentService } from 'medusa-interfaces'
+import {
+  BaseNotificationService,
+  BaseFulfillmentService,
+  BasePaymentService,
+} from "medusa-interfaces"
 import { currencies } from "../utils/currencies"
 import { countries } from "../utils/countries"
 import { AwilixContainer } from "awilix"
@@ -15,11 +19,15 @@ import {
   TaxProviderService,
 } from "../services"
 import { CurrencyRepository } from "../repositories/currency"
-import { AbstractTaxService } from "../interfaces"
 import { FlagRouter } from "../utils/flag-router";
 import SalesChannelFeatureFlag from "./feature-flags/sales-channels";
+import { AbstractPaymentService, AbstractTaxService } from "../interfaces"
 
-const silentResolution = <T>(container: AwilixContainer, name: string, logger: Logger): T | never | undefined => {
+const silentResolution = <T>(
+  container: AwilixContainer,
+  name: string,
+  logger: Logger
+): T | never | undefined => {
   try {
     return container.resolve<T>(name)
   } catch (err) {
@@ -44,15 +52,23 @@ const silentResolution = <T>(container: AwilixContainer, name: string, logger: L
         `You don't have any ${identifier} provider plugins installed. You may want to add one to your project.`
       )
     }
-    return;
+    return
   }
 }
 
-export default async ({ container }: { container: AwilixContainer }): Promise<void> => {
+export default async ({
+  container,
+}: {
+  container: AwilixContainer
+}): Promise<void> => {
   const storeService = container.resolve<StoreService>("storeService")
-  const currencyRepository = container.resolve<typeof CurrencyRepository>("currencyRepository")
-  const countryRepository = container.resolve<typeof CountryRepository>("countryRepository")
-  const profileService = container.resolve<ShippingProfileService>("shippingProfileService")
+  const currencyRepository =
+    container.resolve<typeof CurrencyRepository>("currencyRepository")
+  const countryRepository =
+    container.resolve<typeof CountryRepository>("countryRepository")
+  const profileService = container.resolve<ShippingProfileService>(
+    "shippingProfileService"
+  )
   const salesChannelService = container.resolve<SalesChannelService>("salesChannelService")
   const logger = container.resolve<Logger>("logger")
   const featureFlagRouter = container.resolve<FlagRouter>("featureFlagRouter")
@@ -104,32 +120,54 @@ export default async ({ container }: { container: AwilixContainer }): Promise<vo
     await storeService.withTransaction(manager).create()
 
     const payProviders =
-      silentResolution<typeof BasePaymentService[]>(container, "paymentProviders", logger) || []
+      silentResolution<(typeof BasePaymentService | AbstractPaymentService<never>)[]>(
+        container,
+        "paymentProviders",
+        logger
+      ) || []
     const payIds = payProviders.map((p) => p.getIdentifier())
 
-    const pProviderService = container.resolve<PaymentProviderService>("paymentProviderService")
+    const pProviderService = container.resolve<PaymentProviderService>(
+      "paymentProviderService"
+    )
     await pProviderService.registerInstalledProviders(payIds)
 
     const notiProviders =
-      silentResolution<typeof BaseNotificationService[]>(container, "notificationProviders", logger) || []
+      silentResolution<typeof BaseNotificationService[]>(
+        container,
+        "notificationProviders",
+        logger
+      ) || []
     const notiIds = notiProviders.map((p) => p.getIdentifier())
 
-    const nProviderService = container.resolve<NotificationService>("notificationService")
+    const nProviderService = container.resolve<NotificationService>(
+      "notificationService"
+    )
     await nProviderService.registerInstalledProviders(notiIds)
 
-
     const fulfilProviders =
-      silentResolution<typeof BaseFulfillmentService[]>(container, "fulfillmentProviders", logger) || []
+      silentResolution<typeof BaseFulfillmentService[]>(
+        container,
+        "fulfillmentProviders",
+        logger
+      ) || []
     const fulfilIds = fulfilProviders.map((p) => p.getIdentifier())
 
-    const fProviderService = container.resolve<FulfillmentProviderService>("fulfillmentProviderService")
+    const fProviderService = container.resolve<FulfillmentProviderService>(
+      "fulfillmentProviderService"
+    )
     await fProviderService.registerInstalledProviders(fulfilIds)
 
     const taxProviders =
-      silentResolution<AbstractTaxService[]>(container, "taxProviders", logger) || []
+      silentResolution<AbstractTaxService[]>(
+        container,
+        "taxProviders",
+        logger
+      ) || []
     const taxIds = taxProviders.map((p) => p.getIdentifier())
 
-    const tProviderService = container.resolve<TaxProviderService>("taxProviderService")
+    const tProviderService =
+      container.resolve<TaxProviderService>("taxProviderService")
     await tProviderService.registerInstalledProviders(taxIds)
 
     await profileService.withTransaction(manager).createDefault()
diff --git a/packages/medusa/src/loaders/plugins.ts b/packages/medusa/src/loaders/plugins.ts
index 98ecaf8ad4..aa16d7c041 100644
--- a/packages/medusa/src/loaders/plugins.ts
+++ b/packages/medusa/src/loaders/plugins.ts
@@ -10,7 +10,6 @@ import {
   FileService,
   FulfillmentService,
   OauthService,
-  PaymentService,
 } from "medusa-interfaces"
 import path from "path"
 import { EntitySchema } from "typeorm"
@@ -20,6 +19,7 @@ import {
   isCartCompletionStrategy,
   isFileService,
   isNotificationService,
+  isPaymentService,
   isPriceSelectionStrategy,
   isSearchService,
   isTaxCalculationStrategy,
@@ -366,7 +366,7 @@ export async function registerServices(
         throw new Error(message)
       }
 
-      if (loaded.prototype instanceof PaymentService) {
+      if (isPaymentService(loaded.prototype)) {
         // Register our payment providers to paymentProviders
         container.registerAdd(
           "paymentProviders",
diff --git a/packages/medusa/src/migrations/1660040729000-payment_session_uniq_cartId_providerId.ts b/packages/medusa/src/migrations/1660040729000-payment_session_uniq_cartId_providerId.ts
new file mode 100644
index 0000000000..d738af3d86
--- /dev/null
+++ b/packages/medusa/src/migrations/1660040729000-payment_session_uniq_cartId_providerId.ts
@@ -0,0 +1,13 @@
+import { MigrationInterface, QueryRunner } from "typeorm"
+
+export class paymentSessionUniqCartIdProviderId1660040729000 implements MigrationInterface {
+  name = "paymentSessionUniqCartIdProviderId1660040729000"
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`CREATE UNIQUE INDEX "UniqPaymentSessionCartIdProviderId" ON "payment_session" ("cart_id", "provider_id")`)
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(`DROP INDEX "UniqPaymentSessionCartIdProviderId"`)
+  }
+}
diff --git a/packages/medusa/src/models/payment-session.ts b/packages/medusa/src/models/payment-session.ts
index b458b26892..2945f11041 100644
--- a/packages/medusa/src/models/payment-session.ts
+++ b/packages/medusa/src/models/payment-session.ts
@@ -22,6 +22,7 @@ export enum PaymentSessionStatus {
 }
 
 @Unique("OneSelected", ["cart_id", "is_selected"])
+@Unique("UniqPaymentSessionCartIdProviderId", ["cart_id", "provider_id"])
 @Entity()
 export class PaymentSession extends BaseEntity {
   @Index()
diff --git a/packages/medusa/src/models/payment.ts b/packages/medusa/src/models/payment.ts
index 607e9a0a40..1fe31488db 100644
--- a/packages/medusa/src/models/payment.ts
+++ b/packages/medusa/src/models/payment.ts
@@ -63,10 +63,10 @@ export class Payment extends BaseEntity {
   data: Record<string, unknown>
 
   @Column({ type: resolveDbType("timestamptz"), nullable: true })
-  captured_at: Date
+  captured_at: Date | string
 
   @Column({ type: resolveDbType("timestamptz"), nullable: true })
-  canceled_at: Date
+  canceled_at: Date | string
 
   @DbAwareColumn({ type: "jsonb", nullable: true })
   metadata: Record<string, unknown>
diff --git a/packages/medusa/src/services/__mocks__/test-pay.js b/packages/medusa/src/services/__mocks__/test-pay.js
new file mode 100644
index 0000000000..34017ceca0
--- /dev/null
+++ b/packages/medusa/src/services/__mocks__/test-pay.js
@@ -0,0 +1,43 @@
+export const testPayServiceMock = {
+  identifier: "test-pay",
+  getIdentifier: "test-pay",
+  withTransaction: function () {
+    return this
+  },
+  getStatus: jest.fn().mockResolvedValue(Promise.resolve("authorised")),
+  retrieveSavedMethods: jest.fn().mockResolvedValue(Promise.resolve([])),
+  getPaymentData: jest.fn().mockResolvedValue(Promise.resolve({})),
+  createPayment: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  retrievePayment: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  updatePayment: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  deletePayment: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  authorizePayment: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  updatePaymentData: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  cancelPayment: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  capturePayment: jest.fn().mockImplementation(() => {
+    return {}
+  }),
+  refundPayment: jest.fn().mockImplementation(() => {
+    return {}
+  })
+}
+
+const mock = jest.fn().mockImplementation(() => {
+  return testPayServiceMock
+})
+
+export default mock
diff --git a/packages/medusa/src/services/__tests__/cart.js b/packages/medusa/src/services/__tests__/cart.js
index b354f11c82..f6e9a5f179 100644
--- a/packages/medusa/src/services/__tests__/cart.js
+++ b/packages/medusa/src/services/__tests__/cart.js
@@ -61,6 +61,8 @@ describe("CartService", () => {
         undefined,
         {
           where: { id: IdMap.getId("emptyCart") },
+          select: undefined,
+          relations: undefined,
         }
       )
     })
diff --git a/packages/medusa/src/services/__tests__/payment-provider.js b/packages/medusa/src/services/__tests__/payment-provider.js
index e071e2fb7f..17eec0ebab 100644
--- a/packages/medusa/src/services/__tests__/payment-provider.js
+++ b/packages/medusa/src/services/__tests__/payment-provider.js
@@ -1,7 +1,8 @@
 import { MockManager, MockRepository } from "medusa-test-utils"
 import PaymentProviderService from "../payment-provider"
+import { testPayServiceMock } from "../__mocks__/test-pay"
 
-describe("ProductService", () => {
+describe("PaymentProviderService", () => {
   describe("retrieveProvider", () => {
     const container = {
       manager: MockManager,
@@ -33,6 +34,9 @@ describe("ProductService", () => {
       manager: MockManager,
       paymentSessionRepository: MockRepository(),
       pp_default_provider: {
+        withTransaction: function () {
+          return this
+        },
         createPayment,
       },
     }
@@ -67,6 +71,9 @@ describe("ProductService", () => {
           }),
       }),
       pp_default_provider: {
+        withTransaction: function () {
+          return this
+        },
         updatePayment,
       },
     }
@@ -97,3 +104,183 @@ describe("ProductService", () => {
     })
   })
 })
+
+describe(`PaymentProviderService`, () => {
+  const container = {
+    manager: MockManager,
+    paymentSessionRepository: MockRepository({
+      findOne: () =>
+        Promise.resolve({
+          id: "session",
+          provider_id: "default_provider",
+          data: {
+            id: "1234",
+          },
+        }),
+    }),
+    paymentRepository: MockRepository({
+      findOne: () =>
+        Promise.resolve({
+          id: "pay_jadazdjk",
+          provider_id: "default_provider",
+          data: {
+            id: "1234",
+          },
+        }),
+      find: () =>
+        Promise.resolve([{
+          id: "pay_jadazdjk",
+          provider_id: "default_provider",
+          data: {
+            id: "1234",
+          },
+          captured_at: new Date(),
+          amount: 100,
+          amount_refunded: 0
+        }]),
+    }),
+    refundRepository: MockRepository(),
+    pp_default_provider: testPayServiceMock,
+  }
+  const providerService = new PaymentProviderService(container)
+
+  afterEach(() => {
+    jest.clearAllMocks()
+  })
+
+  it("successfully retrieves payment provider", () => {
+    const provider = providerService.retrieveProvider("default_provider")
+    expect(provider.identifier).toEqual("test-pay")
+  })
+
+  it("successfully creates session", async () => {
+    await providerService.createSession("default_provider", {
+      total: 100,
+    })
+
+    expect(testPayServiceMock.createPayment).toBeCalledTimes(1)
+    expect(testPayServiceMock.createPayment).toBeCalledWith({
+      total: 100,
+    })
+  })
+
+  it("successfully update session", async () => {
+    await providerService.updateSession(
+      {
+        id: "session",
+        provider_id: "default_provider",
+        data: {
+          id: "1234",
+        },
+      },
+      {
+        total: 100,
+      }
+    )
+
+    expect(testPayServiceMock.updatePayment).toBeCalledTimes(1)
+    expect(testPayServiceMock.updatePayment).toBeCalledWith(
+      { id: "1234" },
+      {
+        total: 100,
+      }
+    )
+  })
+
+  it("successfully refresh session", async () => {
+    await providerService.refreshSession(
+      {
+        id: "session",
+        provider_id: "default_provider",
+        data: {
+          id: "1234",
+        },
+      },
+      {
+        total: 100,
+      }
+    )
+
+    expect(testPayServiceMock.deletePayment).toBeCalledTimes(1)
+    expect(testPayServiceMock.createPayment).toBeCalledTimes(1)
+  })
+
+  it("successfully delete session", async () => {
+    await providerService.deleteSession(
+      {
+        id: "session",
+        provider_id: "default_provider",
+        data: {
+          id: "1234",
+        },
+      }
+    )
+
+    expect(testPayServiceMock.deletePayment).toBeCalledTimes(1)
+  })
+
+  it("successfully delete session", async () => {
+    await providerService.deleteSession(
+      {
+        id: "session",
+        provider_id: "default_provider",
+        data: {
+          id: "1234",
+        },
+      }
+    )
+
+    expect(testPayServiceMock.deletePayment).toBeCalledTimes(1)
+  })
+
+  it("successfully authorize payment", async () => {
+    await providerService.authorizePayment(
+      {
+        id: "session",
+        provider_id: "default_provider",
+        data: {
+          id: "1234",
+        },
+      },
+      {}
+    )
+
+    expect(testPayServiceMock.authorizePayment).toBeCalledTimes(1)
+  })
+
+  it("successfully update session data", async () => {
+    await providerService.updateSessionData(
+      {
+        id: "session",
+        provider_id: "default_provider",
+        data: {
+          id: "1234",
+        },
+      },
+      {}
+    )
+
+    expect(testPayServiceMock.updatePaymentData).toBeCalledTimes(1)
+  })
+
+  it("successfully cancel payment", async () => {
+    await providerService.cancelPayment({
+      id: "pay_jadazdjk"
+    })
+    expect(testPayServiceMock.cancelPayment).toBeCalledTimes(1)
+  })
+
+  it("successfully capture payment", async () => {
+    await providerService.capturePayment({
+      id: "pay_jadazdjk"
+    })
+    expect(testPayServiceMock.capturePayment).toBeCalledTimes(1)
+  })
+
+  it("successfully refund payment", async () => {
+    await providerService.refundPayment([{
+      id: "pay_jadazdjk"
+    }], 50)
+    expect(testPayServiceMock.refundPayment).toBeCalledTimes(1)
+  })
+})
diff --git a/packages/medusa/src/services/__tests__/swap.js b/packages/medusa/src/services/__tests__/swap.js
index aaf1a4330e..ebf3df9733 100644
--- a/packages/medusa/src/services/__tests__/swap.js
+++ b/packages/medusa/src/services/__tests__/swap.js
@@ -1,4 +1,3 @@
-import paymentService from "medusa-interfaces/dist/payment-service"
 import { IdMap, MockRepository, MockManager } from "medusa-test-utils"
 import SwapService from "../swap"
 import { InventoryServiceMock } from "../__mocks__/inventory"
diff --git a/packages/medusa/src/services/cart.ts b/packages/medusa/src/services/cart.ts
index bc8ee5d24d..8caa2acdb4 100644
--- a/packages/medusa/src/services/cart.ts
+++ b/packages/medusa/src/services/cart.ts
@@ -4,7 +4,6 @@ import { DeepPartial, EntityManager, In } from "typeorm"
 import { TransactionBaseService } from "../interfaces"
 import { IPriceSelectionStrategy } from "../interfaces/price-selection-strategy"
 import {
-  DiscountRuleType,
   Address,
   Cart,
   CustomShippingOption,
@@ -13,6 +12,8 @@ import {
   LineItem,
   ShippingMethod,
   SalesChannel,
+  DiscountRuleType,
+  PaymentSession,
 } from "../models"
 import { AddressRepository } from "../repositories/address"
 import { CartRepository } from "../repositories/cart"
@@ -1310,7 +1311,10 @@ class CartService extends TransactionBaseService<CartService> {
    * @param update - the data to update the payment session with
    * @return the resulting cart
    */
-  async updatePaymentSession(cartId: string, update: object): Promise<Cart> {
+  async updatePaymentSession(
+    cartId: string,
+    update: Record<string, unknown>
+  ): Promise<Cart> {
     return await this.atomicPhase_(
       async (transactionManager: EntityManager) => {
         const cart = await this.retrieve(cartId, {
@@ -1385,14 +1389,14 @@ class CartService extends TransactionBaseService<CartService> {
           )
         }
 
-        const session = await this.paymentProviderService_
+        const session = (await this.paymentProviderService_
           .withTransaction(transactionManager)
-          .authorizePayment(cart.payment_session, context)
+          .authorizePayment(cart.payment_session, context)) as PaymentSession
 
-        const freshCart = await this.retrieve(cart.id, {
+        const freshCart = (await this.retrieve(cart.id, {
           select: ["total"],
           relations: ["payment_sessions", "items", "items.adjustments"],
-        })
+        })) as Cart & { payment_session: PaymentSession }
 
         if (session.status === "authorized") {
           freshCart.payment = await this.paymentProviderService_
diff --git a/packages/medusa/src/services/order.ts b/packages/medusa/src/services/order.ts
index c68bb4a4f9..f99105e0bc 100644
--- a/packages/medusa/src/services/order.ts
+++ b/packages/medusa/src/services/order.ts
@@ -30,6 +30,7 @@ import {
   Order,
   OrderStatus,
   Payment,
+  PaymentSession,
   PaymentStatus,
   Return,
   Swap,
@@ -531,7 +532,6 @@ class OrderService extends TransactionBaseService<OrderService> {
       // Would be the case if a discount code is applied that covers the item
       // total
       if (total !== 0) {
-        // Throw if payment method does not exist
         if (!payment) {
           throw new MedusaError(
             MedusaError.Types.INVALID_ARGUMENT,
@@ -543,7 +543,6 @@ class OrderService extends TransactionBaseService<OrderService> {
           .withTransaction(manager)
           .getStatus(payment)
 
-        // If payment status is not authorized, we throw
         if (paymentStatus !== "authorized") {
           throw new MedusaError(
             MedusaError.Types.INVALID_ARGUMENT,
diff --git a/packages/medusa/src/services/payment-provider.js b/packages/medusa/src/services/payment-provider.js
deleted file mode 100644
index 613811d59c..0000000000
--- a/packages/medusa/src/services/payment-provider.js
+++ /dev/null
@@ -1,438 +0,0 @@
-import { BaseService } from "medusa-interfaces"
-import { MedusaError } from "medusa-core-utils"
-
-/**
- * Helps retrive payment providers
- */
-class PaymentProviderService extends BaseService {
-  constructor(container) {
-    super()
-
-    /** @private {logger} */
-    this.container_ = container
-
-    this.manager_ = container.manager
-
-    this.paymentSessionRepository_ = container.paymentSessionRepository
-
-    this.paymentRepository_ = container.paymentRepository
-
-    this.refundRepository_ = container.refundRepository
-  }
-
-  withTransaction(manager) {
-    if (!manager) {
-      return this
-    }
-
-    const cloned = new PaymentProviderService(this.container_)
-    cloned.transactionManager_ = manager
-    cloned.manager_ = manager
-
-    return cloned
-  }
-
-  async registerInstalledProviders(providers) {
-    const { manager, paymentProviderRepository } = this.container_
-
-    const model = manager.getCustomRepository(paymentProviderRepository)
-    await model.update({}, { is_installed: false })
-
-    for (const p of providers) {
-      const n = model.create({ id: p, is_installed: true })
-      await model.save(n)
-    }
-  }
-
-  async list() {
-    const { manager, paymentProviderRepository } = this.container_
-    const ppRepo = manager.getCustomRepository(paymentProviderRepository)
-
-    return await ppRepo.find({})
-  }
-
-  async retrievePayment(id, relations = []) {
-    const paymentRepo = this.manager_.getCustomRepository(
-      this.paymentRepository_
-    )
-    const validatedId = this.validateId_(id)
-
-    const query = {
-      where: { id: validatedId },
-    }
-
-    if (relations.length) {
-      query.relations = relations
-    }
-
-    const payment = await paymentRepo.findOne(query)
-
-    if (!payment) {
-      throw new MedusaError(
-        MedusaError.Types.NOT_FOUND,
-        `Payment with ${id} was not found`
-      )
-    }
-
-    return payment
-  }
-
-  listPayments(
-    selector,
-    config = { skip: 0, take: 50, order: { created_at: "DESC" } }
-  ) {
-    const payRepo = this.manager_.getCustomRepository(this.paymentRepository_)
-    const query = this.buildQuery_(selector, config)
-    return payRepo.find(query)
-  }
-
-  async retrieveSession(id, relations = []) {
-    const sessionRepo = this.manager_.getCustomRepository(
-      this.paymentSessionRepository_
-    )
-    const validatedId = this.validateId_(id)
-
-    const query = {
-      where: { id: validatedId },
-    }
-
-    if (relations.length) {
-      query.relations = relations
-    }
-
-    const session = await sessionRepo.findOne(query)
-
-    if (!session) {
-      throw new MedusaError(
-        MedusaError.Types.NOT_FOUND,
-        `Payment Session with ${id} was not found`
-      )
-    }
-
-    return session
-  }
-
-  /**
-   * Creates a payment session with the given provider.
-   * @param {string} providerId - the id of the provider to create payment with
-   * @param {Cart} cart - a cart object used to calculate the amount, etc. from
-   * @return {Promise} the payment session
-   */
-  async createSession(providerId, cart) {
-    return this.atomicPhase_(async (manager) => {
-      const provider = this.retrieveProvider(providerId)
-      const sessionData = await provider.createPayment(cart)
-
-      const sessionRepo = manager.getCustomRepository(
-        this.paymentSessionRepository_
-      )
-
-      const toCreate = {
-        cart_id: cart.id,
-        provider_id: providerId,
-        data: sessionData,
-        status: "pending",
-      }
-
-      const created = sessionRepo.create(toCreate)
-      const result = await sessionRepo.save(created)
-
-      return result
-    })
-  }
-
-  /**
-   * Refreshes a payment session with the given provider.
-   * This means, that we delete the current one and create a new.
-   * @param {PaymentSession} paymentSession - the payment session object to
-   *    update
-   * @param {Cart} cart - a cart object used to calculate the amount, etc. from
-   * @return {Promise} the payment session
-   */
-  async refreshSession(paymentSession, cart) {
-    return this.atomicPhase_(async (manager) => {
-      const session = await this.retrieveSession(paymentSession.id)
-
-      const provider = this.retrieveProvider(paymentSession.provider_id)
-      await provider.deletePayment(session)
-
-      const sessionRepo = manager.getCustomRepository(
-        this.paymentSessionRepository_
-      )
-
-      await sessionRepo.remove(session)
-
-      const sessionData = await provider.createPayment(cart)
-      const toCreate = {
-        cart_id: cart.id,
-        provider_id: session.provider_id,
-        data: sessionData,
-        is_selected: true,
-        status: "pending",
-      }
-
-      const created = sessionRepo.create(toCreate)
-      const result = await sessionRepo.save(created)
-
-      return result
-    })
-  }
-
-  /**
-   * Updates an existing payment session.
-   * @param {PaymentSession} paymentSession - the payment session object to
-   *    update
-   * @param {Cart} cart - the cart object to update for
-   * @return {Promise} the updated payment session
-   */
-  updateSession(paymentSession, cart) {
-    return this.atomicPhase_(async (manager) => {
-      const session = await this.retrieveSession(paymentSession.id)
-
-      const provider = this.retrieveProvider(paymentSession.provider_id)
-      session.data = await provider.updatePayment(paymentSession.data, cart)
-
-      const sessionRepo = manager.getCustomRepository(
-        this.paymentSessionRepository_
-      )
-      return sessionRepo.save(session)
-    })
-  }
-
-  deleteSession(paymentSession) {
-    return this.atomicPhase_(async (manager) => {
-      const session = await this.retrieveSession(paymentSession.id).catch(
-        (_) => undefined
-      )
-
-      if (!session) {
-        return Promise.resolve()
-      }
-
-      const provider = this.retrieveProvider(paymentSession.provider_id)
-      await provider.deletePayment(paymentSession)
-
-      const sessionRepo = manager.getCustomRepository(
-        this.paymentSessionRepository_
-      )
-
-      return sessionRepo.remove(session)
-    })
-  }
-
-  /**
-   * Finds a provider given an id
-   * @param {string} providerId - the id of the provider to get
-   * @return {PaymentService} the payment provider
-   */
-  retrieveProvider(providerId) {
-    try {
-      let provider
-      if (providerId === "system") {
-        provider = this.container_[`systemPaymentProviderService`]
-      } else {
-        provider = this.container_[`pp_${providerId}`]
-      }
-
-      return provider
-    } catch (err) {
-      throw new MedusaError(
-        MedusaError.Types.NOT_FOUND,
-        `Could not find a payment provider with id: ${providerId}`
-      )
-    }
-  }
-
-  async createPayment(cart) {
-    return this.atomicPhase_(async (manager) => {
-      const { payment_session: paymentSession, region, total } = cart
-      const provider = this.retrieveProvider(paymentSession.provider_id)
-      const paymentData = await provider.getPaymentData(paymentSession)
-
-      const paymentRepo = manager.getCustomRepository(this.paymentRepository_)
-
-      const created = paymentRepo.create({
-        provider_id: paymentSession.provider_id,
-        amount: total,
-        currency_code: region.currency_code,
-        data: paymentData,
-        cart_id: cart.id,
-      })
-
-      return paymentRepo.save(created)
-    })
-  }
-
-  async updatePayment(paymentId, update) {
-    return this.atomicPhase_(async (manager) => {
-      const payment = await this.retrievePayment(paymentId)
-
-      if ("order_id" in update) {
-        payment.order_id = update.order_id
-      }
-
-      if ("swap_id" in update) {
-        payment.swap_id = update.swap_id
-      }
-
-      const payRepo = manager.getCustomRepository(this.paymentRepository_)
-      return payRepo.save(payment)
-    })
-  }
-
-  async authorizePayment(paymentSession, context) {
-    return this.atomicPhase_(async (manager) => {
-      const session = await this.retrieveSession(paymentSession.id).catch(
-        (_) => undefined
-      )
-
-      if (!session) {
-        return Promise.resolve()
-      }
-
-      const provider = this.retrieveProvider(paymentSession.provider_id)
-      const { status, data } = await provider
-        .withTransaction(manager)
-        .authorizePayment(session, context)
-
-      session.data = data
-      session.status = status
-
-      const sessionRepo = manager.getCustomRepository(
-        this.paymentSessionRepository_
-      )
-      return sessionRepo.save(session)
-    })
-  }
-
-  async updateSessionData(paySession, update) {
-    return this.atomicPhase_(async (manager) => {
-      const session = await this.retrieveSession(paySession.id)
-
-      const provider = this.retrieveProvider(paySession.provider_id)
-
-      session.data = await provider.updatePaymentData(paySession.data, update)
-      session.status = paySession.status
-
-      const sessionRepo = manager.getCustomRepository(
-        this.paymentSessionRepository_
-      )
-      return sessionRepo.save(session)
-    })
-  }
-
-  async cancelPayment(paymentObj) {
-    return this.atomicPhase_(async (manager) => {
-      const payment = await this.retrievePayment(paymentObj.id)
-      const provider = this.retrieveProvider(payment.provider_id)
-      payment.data = await provider.cancelPayment(payment)
-
-      const now = new Date()
-      payment.canceled_at = now.toISOString()
-
-      const paymentRepo = manager.getCustomRepository(this.paymentRepository_)
-      return await paymentRepo.save(payment)
-    })
-  }
-
-  async getStatus(payment) {
-    const provider = this.retrieveProvider(payment.provider_id)
-    return provider.getStatus(payment.data)
-  }
-
-  async capturePayment(paymentObj) {
-    return this.atomicPhase_(async (manager) => {
-      const payment = await this.retrievePayment(paymentObj.id)
-
-      const provider = this.retrieveProvider(payment.provider_id)
-      payment.data = await provider.capturePayment(payment)
-
-      const now = new Date()
-      payment.captured_at = now.toISOString()
-
-      const paymentRepo = manager.getCustomRepository(this.paymentRepository_)
-      return paymentRepo.save(payment)
-    })
-  }
-
-  async refundPayment(payObjs, amount, reason, note) {
-    return this.atomicPhase_(async (manager) => {
-      const payments = await this.listPayments({ id: payObjs.map((p) => p.id) })
-
-      let order_id
-      const refundable = payments.reduce((acc, next) => {
-        order_id = next.order_id
-        if (next.captured_at) {
-          return (acc += next.amount - next.amount_refunded)
-        }
-
-        return acc
-      }, 0)
-
-      if (refundable < amount) {
-        throw new MedusaError(
-          MedusaError.Types.NOT_ALLOWED,
-          "Refund amount is too high"
-        )
-      }
-
-      let balance = amount
-
-      const used = []
-
-      const paymentRepo = manager.getCustomRepository(this.paymentRepository_)
-      let toRefund = payments.find((p) => p.amount - p.amount_refunded > 0)
-      while (toRefund) {
-        const currentRefundable = toRefund.amount - toRefund.amount_refunded
-
-        const refundAmount = Math.min(currentRefundable, balance)
-
-        const provider = this.retrieveProvider(toRefund.provider_id)
-        toRefund.data = await provider.refundPayment(toRefund, refundAmount)
-        toRefund.amount_refunded += refundAmount
-        await paymentRepo.save(toRefund)
-
-        balance -= refundAmount
-
-        used.push(toRefund.id)
-
-        if (balance > 0) {
-          toRefund = payments.find(
-            (p) => p.amount - p.amount_refunded > 0 && !used.includes(p.id)
-          )
-        } else {
-          toRefund = null
-        }
-      }
-
-      const refundRepo = manager.getCustomRepository(this.refundRepository_)
-
-      const toCreate = {
-        order_id,
-        amount,
-        reason,
-        note,
-      }
-
-      const created = refundRepo.create(toCreate)
-      return refundRepo.save(created)
-    })
-  }
-
-  async retrieveRefund(id, config = {}) {
-    const refRepo = this.manager_.getCustomRepository(this.refundRepository_)
-    const query = this.buildQuery_({ id }, config)
-    const refund = await refRepo.findOne(query)
-
-    if (!refund) {
-      throw new MedusaError(
-        MedusaError.Types.NOT_FOUND,
-        `A refund with ${id} was not found`
-      )
-    }
-
-    return refund
-  }
-}
-
-export default PaymentProviderService
diff --git a/packages/medusa/src/services/payment-provider.ts b/packages/medusa/src/services/payment-provider.ts
new file mode 100644
index 0000000000..b3f5de7cb3
--- /dev/null
+++ b/packages/medusa/src/services/payment-provider.ts
@@ -0,0 +1,544 @@
+import { MedusaError } from "medusa-core-utils"
+import { BasePaymentService } from "medusa-interfaces"
+import { AbstractPaymentService, TransactionBaseService } from "../interfaces"
+import { EntityManager } from "typeorm"
+import { PaymentSessionRepository } from "../repositories/payment-session"
+import { PaymentRepository } from "../repositories/payment"
+import { RefundRepository } from "../repositories/refund"
+import { PaymentProviderRepository } from "../repositories/payment-provider"
+import { buildQuery } from "../utils"
+import { FindConfig, Selector } from "../types/common"
+import {
+  Cart,
+  Payment,
+  PaymentProvider,
+  PaymentSession,
+  PaymentSessionStatus,
+  Refund,
+} from "../models"
+
+type PaymentProviderKey = `pp_${string}` | "systemPaymentProviderService"
+type InjectedDependencies = {
+  manager: EntityManager
+  paymentSessionRepository: typeof PaymentSessionRepository
+  paymentProviderRepository: typeof PaymentProviderRepository
+  paymentRepository: typeof PaymentRepository
+  refundRepository: typeof RefundRepository
+} & {
+  [key in `${PaymentProviderKey}`]:
+    | AbstractPaymentService<never>
+    | typeof BasePaymentService
+}
+
+/**
+ * Helps retrieve payment providers
+ */
+export default class PaymentProviderService extends TransactionBaseService<PaymentProviderService> {
+  protected manager_: EntityManager
+  protected transactionManager_: EntityManager | undefined
+  protected readonly container_: InjectedDependencies
+  protected readonly paymentSessionRepository_: typeof PaymentSessionRepository
+  protected readonly paymentProviderRepository_: typeof PaymentProviderRepository
+  protected readonly paymentRepository_: typeof PaymentRepository
+  protected readonly refundRepository_: typeof RefundRepository
+
+  constructor(container: InjectedDependencies) {
+    super(container)
+
+    this.container_ = container
+    this.manager_ = container.manager
+    this.paymentSessionRepository_ = container.paymentSessionRepository
+    this.paymentProviderRepository_ = container.paymentProviderRepository
+    this.paymentRepository_ = container.paymentRepository
+    this.refundRepository_ = container.refundRepository
+  }
+
+  async registerInstalledProviders(providerIds: string[]): Promise<void> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const model = transactionManager.getCustomRepository(
+        this.paymentProviderRepository_
+      )
+      await model.update({}, { is_installed: false })
+
+      await Promise.all(
+        providerIds.map(async (providerId) => {
+          const provider = model.create({
+            id: providerId,
+            is_installed: true,
+          })
+          return await model.save(provider)
+        })
+      )
+    })
+  }
+
+  async list(): Promise<PaymentProvider[]> {
+    const ppRepo = this.manager_.getCustomRepository(
+      this.paymentProviderRepository_
+    )
+    return await ppRepo.find()
+  }
+
+  async retrievePayment(
+    id: string,
+    relations: string[] = []
+  ): Promise<Payment | never> {
+    const paymentRepo = this.manager_.getCustomRepository(
+      this.paymentRepository_
+    )
+    const query = {
+      where: { id },
+      relations: [] as string[],
+    }
+
+    if (relations.length) {
+      query.relations = relations
+    }
+
+    const payment = await paymentRepo.findOne(query)
+
+    if (!payment) {
+      throw new MedusaError(
+        MedusaError.Types.NOT_FOUND,
+        `Payment with ${id} was not found`
+      )
+    }
+
+    return payment
+  }
+
+  async listPayments(
+    selector: Selector<Payment>,
+    config: FindConfig<Payment> = {
+      skip: 0,
+      take: 50,
+      order: { created_at: "DESC" },
+    }
+  ): Promise<Payment[]> {
+    const payRepo = this.manager_.getCustomRepository(this.paymentRepository_)
+    const query = buildQuery(selector, config)
+    return await payRepo.find(query)
+  }
+
+  async retrieveSession(
+    id: string,
+    relations: string[] = []
+  ): Promise<PaymentSession | never> {
+    const sessionRepo = this.manager_.getCustomRepository(
+      this.paymentSessionRepository_
+    )
+
+    const query = {
+      where: { id },
+      relations: [] as string[],
+    }
+
+    if (relations.length) {
+      query.relations = relations
+    }
+
+    const session = await sessionRepo.findOne(query)
+
+    if (!session) {
+      throw new MedusaError(
+        MedusaError.Types.NOT_FOUND,
+        `Payment Session with ${id} was not found`
+      )
+    }
+
+    return session
+  }
+
+  /**
+   * Creates a payment session with the given provider.
+   * @param providerId - the id of the provider to create payment with
+   * @param cart - a cart object used to calculate the amount, etc. from
+   * @return the payment session
+   */
+  async createSession(providerId: string, cart: Cart): Promise<PaymentSession> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const provider = this.retrieveProvider(providerId)
+      const sessionData = await provider
+        .withTransaction(transactionManager)
+        .createPayment(cart)
+
+      const sessionRepo = transactionManager.getCustomRepository(
+        this.paymentSessionRepository_
+      )
+
+      const toCreate = {
+        cart_id: cart.id,
+        provider_id: providerId,
+        data: sessionData,
+        status: "pending",
+      }
+
+      const created = sessionRepo.create(toCreate)
+      return await sessionRepo.save(created)
+    })
+  }
+
+  /**
+   * Refreshes a payment session with the given provider.
+   * This means, that we delete the current one and create a new.
+   * @param paymentSession - the payment session object to
+   *    update
+   * @param cart - a cart object used to calculate the amount, etc. from
+   * @return the payment session
+   */
+  async refreshSession(
+    paymentSession: PaymentSession,
+    cart: Cart
+  ): Promise<PaymentSession> {
+    return this.atomicPhase_(async (transactionManager) => {
+      const session = await this.retrieveSession(paymentSession.id)
+      const provider = this.retrieveProvider(paymentSession.provider_id)
+      await provider.withTransaction(transactionManager).deletePayment(session)
+
+      const sessionRepo = transactionManager.getCustomRepository(
+        this.paymentSessionRepository_
+      )
+
+      await sessionRepo.remove(session)
+
+      const sessionData = await provider
+        .withTransaction(transactionManager)
+        .createPayment(cart)
+
+      const toCreate = {
+        cart_id: cart.id,
+        provider_id: session.provider_id,
+        data: sessionData,
+        is_selected: true,
+        status: "pending",
+      }
+
+      const created = sessionRepo.create(toCreate)
+      return await sessionRepo.save(created)
+    })
+  }
+
+  /**
+   * Updates an existing payment session.
+   * @param paymentSession - the payment session object to
+   *    update
+   * @param cart - the cart object to update for
+   * @return the updated payment session
+   */
+  async updateSession(
+    paymentSession: PaymentSession,
+    cart: Cart
+  ): Promise<PaymentSession> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const session = await this.retrieveSession(paymentSession.id)
+      const provider = this.retrieveProvider(paymentSession.provider_id)
+      session.data = await provider
+        .withTransaction(transactionManager)
+        .updatePayment(paymentSession.data, cart)
+
+      const sessionRepo = transactionManager.getCustomRepository(
+        this.paymentSessionRepository_
+      )
+      return sessionRepo.save(session)
+    })
+  }
+
+  async deleteSession(
+    paymentSession: PaymentSession
+  ): Promise<PaymentSession | undefined> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const session = await this.retrieveSession(paymentSession.id).catch(
+        () => void 0
+      )
+
+      if (!session) {
+        return
+      }
+
+      const provider = this.retrieveProvider(paymentSession.provider_id)
+      await provider
+        .withTransaction(transactionManager)
+        .deletePayment(paymentSession)
+
+      const sessionRepo = transactionManager.getCustomRepository(
+        this.paymentSessionRepository_
+      )
+
+      return sessionRepo.remove(session)
+    })
+  }
+
+  /**
+   * Finds a provider given an id
+   * @param {string} providerId - the id of the provider to get
+   * @return {PaymentService} the payment provider
+   */
+  retrieveProvider<
+    TProvider extends AbstractPaymentService<never> | typeof BasePaymentService
+  >(
+    providerId: string
+  ): TProvider extends AbstractPaymentService<never>
+    ? AbstractPaymentService<never>
+    : typeof BasePaymentService {
+    try {
+      let provider
+      if (providerId === "system") {
+        provider = this.container_[`systemPaymentProviderService`]
+      } else {
+        provider = this.container_[`pp_${providerId}`]
+      }
+
+      return provider
+    } catch (err) {
+      throw new MedusaError(
+        MedusaError.Types.NOT_FOUND,
+        `Could not find a payment provider with id: ${providerId}`
+      )
+    }
+  }
+
+  async createPayment(
+    cart: Cart & { payment_session: PaymentSession }
+  ): Promise<Payment> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const { payment_session: paymentSession, region, total } = cart
+
+      const provider = this.retrieveProvider(paymentSession.provider_id)
+      const paymentData = await provider
+        .withTransaction(transactionManager)
+        .getPaymentData(paymentSession)
+
+      const paymentRepo = transactionManager.getCustomRepository(
+        this.paymentRepository_
+      )
+
+      const created = paymentRepo.create({
+        provider_id: paymentSession.provider_id,
+        amount: total,
+        currency_code: region.currency_code,
+        data: paymentData,
+        cart_id: cart.id,
+      })
+
+      return paymentRepo.save(created)
+    })
+  }
+
+  async updatePayment(
+    paymentId: string,
+    data: { order_id?: string; swap_id?: string }
+  ): Promise<Payment> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const payment = await this.retrievePayment(paymentId)
+
+      if (data?.order_id) {
+        payment.order_id = data.order_id
+      }
+
+      if (data?.swap_id) {
+        payment.swap_id = data.swap_id
+      }
+
+      const payRepo = transactionManager.getCustomRepository(
+        this.paymentRepository_
+      )
+      return payRepo.save(payment)
+    })
+  }
+
+  async authorizePayment(
+    paymentSession: PaymentSession,
+    context: Record<string, unknown>
+  ): Promise<PaymentSession | undefined> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const session = await this.retrieveSession(paymentSession.id).catch(
+        () => void 0
+      )
+
+      if (!session) {
+        return
+      }
+
+      const provider = this.retrieveProvider(paymentSession.provider_id)
+      const { status, data } = await provider
+        .withTransaction(transactionManager)
+        .authorizePayment(session, context)
+
+      session.data = data
+      session.status = status
+
+      const sessionRepo = transactionManager.getCustomRepository(
+        this.paymentSessionRepository_
+      )
+      return sessionRepo.save(session)
+    })
+  }
+
+  async updateSessionData(
+    paymentSession: PaymentSession,
+    data: Record<string, unknown>
+  ): Promise<PaymentSession> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const session = await this.retrieveSession(paymentSession.id)
+
+      const provider = this.retrieveProvider(paymentSession.provider_id)
+
+      session.data = await provider
+        .withTransaction(transactionManager)
+        .updatePaymentData(paymentSession.data, data)
+      session.status = paymentSession.status
+
+      const sessionRepo = transactionManager.getCustomRepository(
+        this.paymentSessionRepository_
+      )
+      return sessionRepo.save(session)
+    })
+  }
+
+  async cancelPayment(
+    paymentObj: Partial<Payment> & { id: string }
+  ): Promise<Payment> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const payment = await this.retrievePayment(paymentObj.id)
+      const provider = this.retrieveProvider(payment.provider_id)
+      payment.data = await provider
+        .withTransaction(transactionManager)
+        .cancelPayment(payment)
+
+      const now = new Date()
+      payment.canceled_at = now.toISOString()
+
+      const paymentRepo = transactionManager.getCustomRepository(
+        this.paymentRepository_
+      )
+      return await paymentRepo.save(payment)
+    })
+  }
+
+  async getStatus(payment: Payment): Promise<PaymentSessionStatus> {
+    const provider = this.retrieveProvider(payment.provider_id)
+    return await provider.withTransaction(this.manager_).getStatus(payment.data)
+  }
+
+  async capturePayment(
+    paymentObj: Partial<Payment> & { id: string }
+  ): Promise<Payment> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const payment = await this.retrievePayment(paymentObj.id)
+      const provider = this.retrieveProvider(payment.provider_id)
+      payment.data = await provider
+        .withTransaction(transactionManager)
+        .capturePayment(payment)
+
+      const now = new Date()
+      payment.captured_at = now.toISOString()
+
+      const paymentRepo = transactionManager.getCustomRepository(
+        this.paymentRepository_
+      )
+      return paymentRepo.save(payment)
+    })
+  }
+
+  async refundPayment(
+    payObjs: Payment[],
+    amount: number,
+    reason: string,
+    note?: string
+  ): Promise<Refund> {
+    return await this.atomicPhase_(async (transactionManager) => {
+      const payments = await this.listPayments({
+        id: payObjs.map((p) => p.id),
+      })
+
+      let order_id!: string
+      const refundable = payments.reduce((acc, next) => {
+        order_id = next.order_id
+        if (next.captured_at) {
+          return (acc += next.amount - next.amount_refunded)
+        }
+
+        return acc
+      }, 0)
+
+      if (refundable < amount) {
+        throw new MedusaError(
+          MedusaError.Types.NOT_ALLOWED,
+          "Refund amount is higher that the refundable amount"
+        )
+      }
+
+      let balance = amount
+
+      const used: string[] = []
+
+      const paymentRepo = transactionManager.getCustomRepository(
+        this.paymentRepository_
+      )
+      let paymentToRefund = payments.find(
+        (payment) => payment.amount - payment.amount_refunded > 0
+      )
+
+      while (paymentToRefund) {
+        const currentRefundable =
+          paymentToRefund.amount - paymentToRefund.amount_refunded
+
+        const refundAmount = Math.min(currentRefundable, balance)
+
+        const provider = this.retrieveProvider(paymentToRefund.provider_id)
+        paymentToRefund.data = await provider
+          .withTransaction(transactionManager)
+          .refundPayment(paymentToRefund, refundAmount)
+
+        paymentToRefund.amount_refunded += refundAmount
+        await paymentRepo.save(paymentToRefund)
+
+        balance -= refundAmount
+
+        used.push(paymentToRefund.id)
+
+        if (balance > 0) {
+          paymentToRefund = payments.find(
+            (payment) =>
+              payment.amount - payment.amount_refunded > 0 &&
+              !used.includes(payment.id)
+          )
+        } else {
+          paymentToRefund = undefined
+        }
+      }
+
+      const refundRepo = transactionManager.getCustomRepository(
+        this.refundRepository_
+      )
+
+      const toCreate = {
+        order_id,
+        amount,
+        reason,
+        note,
+      }
+
+      const created = refundRepo.create(toCreate)
+      return refundRepo.save(created)
+    })
+  }
+
+  async retrieveRefund(
+    id: string,
+    config: FindConfig<Refund> = {}
+  ): Promise<Refund | never> {
+    const refRepo = this.manager_.getCustomRepository(this.refundRepository_)
+    const query = buildQuery({ id }, config)
+    const refund = await refRepo.findOne(query)
+
+    if (!refund) {
+      throw new MedusaError(
+        MedusaError.Types.NOT_FOUND,
+        `A refund with ${id} was not found`
+      )
+    }
+
+    return refund
+  }
+}
diff --git a/packages/medusa/src/services/system-payment-provider.js b/packages/medusa/src/services/system-payment-provider.js
index f8254b99dc..737c7490a0 100644
--- a/packages/medusa/src/services/system-payment-provider.js
+++ b/packages/medusa/src/services/system-payment-provider.js
@@ -1,10 +1,10 @@
-import { BaseService } from "medusa-interfaces"
+import { TransactionBaseService } from "../interfaces"
 
-class SystemProviderService extends BaseService {
+class SystemProviderService extends TransactionBaseService {
   static identifier = "system"
 
   constructor(_) {
-    super()
+    super(_)
   }
 
   async createPayment(_) {
diff --git a/packages/medusa/tsconfig.json b/packages/medusa/tsconfig.json
index c54526fd0d..0fc6130e78 100644
--- a/packages/medusa/tsconfig.json
+++ b/packages/medusa/tsconfig.json
@@ -22,14 +22,11 @@
     "skipLibCheck": true,
     "downlevelIteration": true // to use ES5 specific tooling
   },
-  "include": [
-    "./src/**/*",
-    "index.d.ts"
-  ],
+  "include": ["./src/**/*", "index.d.ts"],
   "exclude": [
     "./dist/**/*",
     "./src/**/__tests__",
     "./src/**/__mocks__",
     "node_modules"
   ]
-}
+}
\ No newline at end of file