After purchasing an app or game on Google Play using your Mobifone account, you can return the app or game within 2 hours of purchase to receive a full refund.
Here is the refund process for Google Play Mobifone on Galaxy J3 Pro:
Step 1: Open Google Play >> find the purchased app >> request a refund.

Step 2: Confirm.

Step 3: Wait a moment for the device to automatically uninstall the app >> after 24 hours, the money will be refunded to your account.

That completes the process of refunding for Google Play Mobifone on Galaxy J3 Pro. Wishing you all success.
See more:
How to Pay on Google Play with Mobifone on Galaxy J3 Pro
How to Remove Google Play Settings with Mobifone on Galaxy J3 Pro
