App purchase
I have a pending purchase for a game how do I end it so I can buy other stuff
If your payment method is declined, or you have a billing issue with a previous purchase in the iTunes Store - https://support.apple.com/HT203005 - various reasons why payment method is declined.
Payment methods you can use in the iTunes Store, App Store, and iBooks Store - https://support.apple.com/HT202631 - Your card is from the same country as the store you are using?