diff --git a/src/modules/discounts/constants/index.ts b/src/modules/discounts/constants/index.ts
index f842723..fe71d92 100644
--- a/src/modules/discounts/constants/index.ts
+++ b/src/modules/discounts/constants/index.ts
@@ -1,10 +1,20 @@
 export const DISCOUNT = Object.freeze({
+  // Queue names
   DISCOUNT_QUEUE_NAME: "discount",
+
+  // Job names
   DISCOUNT_DEACTIVATE_JOB_NAME: "deactivateDiscount",
-  //
+
+  // Job configurations
   DISCOUNT_DEACTIVATE_JOB_PRIORITY: 1, // high priority
   DISCOUNT_DEACTIVATE_JOB_ATTEMPTS: 3, // 3 times
   DISCOUNT_DEACTIVATE_JOB_BACKOFF: 5 * 1000, // ms
   DISCOUNT_DEACTIVATE_JOB_TIMEOUT: 10000, // timeout after 10 seconds
-  //
+
+  // Discount deactivation messages
+  DISCOUNT_DEACTIVATION_SUCCESS: "Discount successfully deactivated",
+  DISCOUNT_DEACTIVATION_ERROR: "Failed to deactivate discount",
+
+  // Discount application types
+  DISCOUNT_APPLICATION_DIRECT: "DIRECT",
 });
diff --git a/src/modules/invoices/providers/invoices.service.ts b/src/modules/invoices/providers/invoices.service.ts
index c667be2..06b2361 100755
--- a/src/modules/invoices/providers/invoices.service.ts
+++ b/src/modules/invoices/providers/invoices.service.ts
@@ -114,7 +114,6 @@ export class InvoicesService {
 
   //********************************** */
 
-  //TODO: fix this
   async updateInvoiceAdmin(invoiceId: string, updateDto: UpdateInvoiceDto) {
     const queryRunner = this.dataSource.createQueryRunner();
 
@@ -158,6 +157,16 @@ export class InvoicesService {
         const user = await this.usersService.findOneByIdWithQueryRunner(updateDto.userId, queryRunner);
         invoice.user = user;
       }
+
+      // Save the updated invoice
+      await queryRunner.manager.save(this.invoiceRepository.target, invoice);
+
+      await queryRunner.commitTransaction();
+
+      return {
+        message: InvoiceMessage.INVOICE_UPDATED,
+        invoice,
+      };
     } catch (error) {
       await queryRunner.rollbackTransaction();
       throw error;
@@ -168,39 +177,48 @@ export class InvoicesService {
   //********************************** */
 
   async approveInvoiceRequest(invoiceId: string, userId: string) {
-    const { user } = await this.usersService.findOneById(userId);
+    const queryRunner = this.dataSource.createQueryRunner();
 
-    const invoice = await this.invoiceRepository.findOne({ where: { id: invoiceId, user: { id: userId } }, relations: { items: true } });
-    if (!invoice) throw new BadRequestException(InvoiceMessage.NOT_FOUND_BY_ID);
+    try {
+      await queryRunner.connect();
+      await queryRunner.startTransaction();
 
-    if (invoice.status === InvoiceStatus.WAIT_PAYMENT) throw new BadRequestException(InvoiceMessage.ALREADY_APPROVED);
-    if (invoice.status === InvoiceStatus.PAID) throw new BadRequestException(InvoiceMessage.INVOICE_ALREADY_PAID);
-    if (dayjs().isAfter(dayjs(invoice.dueDate).add(INVOICE.MAX_DAYS_AFTER_OVERDUE, "day"))) {
-      invoice.status = InvoiceStatus.EXPIRED;
-      await this.invoiceRepository.save(invoice);
-      throw new BadRequestException(InvoiceMessage.INVOICE_IS_OVERDUE);
-    }
+      const user = await this.usersService.findOneByIdWithQueryRunner(userId, queryRunner);
 
-    if (invoice.status !== InvoiceStatus.PENDING) throw new BadRequestException(InvoiceMessage.INVOICE_CAN_NOT_APPROVED);
+      const invoice = await this.validateInvoiceForApproval(invoiceId, userId, queryRunner);
+
+      const existCode = await this.otpService.checkExistOtp(user.phone, "INVOICE_VERIFY");
+      if (existCode) {
+        return {
+          message: AuthMessage.OTP_ALREADY_SENT,
+          ttlSecond: existCode,
+        };
+      }
+
+      // Generate and send OTP
+      const otpCode = await this.otpService.generateAndSetInCache(user.phone, "INVOICE_VERIFY");
+      const items = invoice.items.map((item) => item.name).join(", ");
+
+      await this.smsService.sendInvoiceVerifyCode(
+        user.phone,
+        otpCode,
+        invoice.numericId,
+        new Decimal(invoice.totalPrice).toNumber(),
+        items,
+      );
+
+      await queryRunner.commitTransaction();
 
-    const existCode = await this.otpService.checkExistOtp(user.phone, "INVOICE_VERIFY");
-    if (existCode) {
       return {
-        message: AuthMessage.OTP_ALREADY_SENT,
-        ttlSecond: existCode,
+        message: AuthMessage.OTP_SENT,
+        otpCode,
       };
+    } catch (error) {
+      await queryRunner.rollbackTransaction();
+      throw error;
+    } finally {
+      await queryRunner.release();
     }
-
-    const otpCode = await this.otpService.generateAndSetInCache(user.phone, "INVOICE_VERIFY");
-    const items = invoice.items.map((item) => item.name).join(", ");
-    //
-    await this.smsService.sendInvoiceVerifyCode(user.phone, otpCode, invoice.numericId, new Decimal(invoice.totalPrice).toNumber(), items);
-    this.logger.debug(`OTP sent to ${user.phone}: ${otpCode}`);
-
-    return {
-      message: AuthMessage.OTP_SENT,
-      otpCode,
-    };
   }
 
   //********************************** */
@@ -213,27 +231,12 @@ export class InvoicesService {
       await queryRunner.startTransaction();
       const { code } = verifyOtpDto;
 
-      const invoice = await queryRunner.manager.findOne(Invoice, {
-        where: { id: invoiceId, user: { id: userId } },
-        relations: { items: true },
-      });
-      if (!invoice) throw new BadRequestException(InvoiceMessage.NOT_FOUND_BY_ID);
-
       const user = await this.usersService.findOneByIdWithQueryRunner(userId, queryRunner);
 
       const isValid = await this.otpService.verifyOtp(user.phone, code, "INVOICE_VERIFY");
       if (!isValid) throw new BadRequestException(AuthMessage.INVALID_OTP);
 
-      if (invoice.status === InvoiceStatus.WAIT_PAYMENT) throw new BadRequestException(InvoiceMessage.ALREADY_APPROVED);
-      if (invoice.status === InvoiceStatus.PAID) throw new BadRequestException(InvoiceMessage.INVOICE_ALREADY_PAID);
-      //
-      if (dayjs().isAfter(dayjs(invoice.dueDate).add(INVOICE.MAX_DAYS_AFTER_OVERDUE, "day"))) {
-        invoice.status = InvoiceStatus.EXPIRED;
-        await this.invoiceRepository.save(invoice);
-        throw new BadRequestException(InvoiceMessage.INVOICE_IS_OVERDUE);
-      }
-      //
-      if (invoice.status !== InvoiceStatus.PENDING) throw new BadRequestException(InvoiceMessage.INVOICE_CAN_NOT_APPROVED);
+      const invoice = await this.validateInvoiceForApproval(invoiceId, userId, queryRunner);
 
       invoice.status = InvoiceStatus.WAIT_PAYMENT;
       await queryRunner.manager.save(Invoice, invoice);
@@ -267,7 +270,33 @@ export class InvoicesService {
       await queryRunner.release();
     }
   }
+
+  //********************************** */
+  private async validateInvoiceForApproval(invoiceId: string, userId: string, queryRunner: QueryRunner): Promise<Invoice> {
+    const invoice = await queryRunner.manager.findOne(Invoice, {
+      where: { id: invoiceId, user: { id: userId } },
+      relations: { items: true },
+    });
+
+    if (!invoice) throw new BadRequestException(InvoiceMessage.NOT_FOUND_BY_ID);
+
+    if (invoice.status === InvoiceStatus.WAIT_PAYMENT) throw new BadRequestException(InvoiceMessage.ALREADY_APPROVED);
+
+    if (invoice.status === InvoiceStatus.PAID) throw new BadRequestException(InvoiceMessage.INVOICE_ALREADY_PAID);
+
+    if (dayjs().isAfter(dayjs(invoice.dueDate).add(INVOICE.MAX_DAYS_AFTER_OVERDUE, "day"))) {
+      invoice.status = InvoiceStatus.EXPIRED;
+      await queryRunner.manager.save(Invoice, invoice);
+      throw new BadRequestException(InvoiceMessage.INVOICE_IS_OVERDUE);
+    }
+
+    if (invoice.status !== InvoiceStatus.PENDING) throw new BadRequestException(InvoiceMessage.INVOICE_CAN_NOT_APPROVED);
+
+    return invoice;
+  }
+
   ///********************************** */
+
   async createInvoiceForSubscription(user: User, plan: SubscriptionPlan, userSub: UserSubscription, dueDate: Date, qryRnr: QueryRunner) {
     const discount = plan.directDiscount;
     const originalPrice = plan.originalPrice || plan.price;