Trying to buy Minecraft using Apple ID funds

You are welcome. If MIncraft has a subscription, you have to have a credit card on file. Are you seeing any error messages?

If necessary, contact iTunes Support for assistance. See the Apple Support articles below for contact information.   

iTunes Support – world wide 

Apple Support schedule phone call     

Billings and Subscriptions 

If necessary, try Twitter

https://twitter.com/AppleSupport.         

Are you buying the game from the App Store? What happens when you try to buy the game? Error message(s)?