(Unknown error has occurred) about confirming payment with my apple account credit

Hey there weiper,

Let's team up to look into getting this resolved. We'd like to learn more about what's happening, along with ruling out some possible causes:

1. Is the entire message only showing 'unknown error has occurred', or does it show additional steps, or even more to the error message?
2. You mentioned this occurs when trying to add credit to your Apple Account balance, but if you've been successful doing this in the past, when did this start?
3. Have you already tried adding balance using a different device? This link shows the steps for doing this for multiple devices: Add money to your Apple Account balance
4. If you don't have another device to try this with, sometimes unexpected behavior can be resolved with a restart. Have you already tried one for your device?

Cheers!