Clarification about App Rejection Message

Hello,

We're currently preparing mobile app focusing on provide online education service. When we're submitting our app in app store we got Rejection message about this 2 issue:

1. Guideline 3.1.1 - Business - Payments - In-App Purchase
Your app unlocks or enables additional functionality with mechanisms other than the App Store, which is not appropriate for the App Store.
Specifically, your app enables the redemption of coupons.

Next Steps
To resolve this issue, please remove this feature from your app.

2. Guideline 3.1.1 - Business - Payments - In-App Purchase
We noticed that your app or its metadata enables the purchase of content, services, or functionality in the app by means other than the in-app purchase API, which is not appropriate for the App Store.
Next Steps
While the payment system that you have included may conduct the transaction outside of the app, if the purchasable content, functionality, or services are intended to be used in the app, they must be purchased using in-app purchase, within the app - unless it is of the type referenced in guideline 3.1.3 of the App Store Review Guidelines.

My Question regarding this is as follow:
  1. How can we use the promo/discount code for some of the content in this app?

  2. Can we use 3 rd party payment gateway for our service?

Appreciate for your response.

Many thanks
Clarification about App Rejection Message
 
 
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