i cannot purchase a game i downloaded from the App store

See these support guides:

Change or remove your Apple ID payment information - Apple Support

or

If you can't choose None when you edit your Apple ID payment information - Apple Support

or

If your payment method is declined, or you have a billing issue in the App Store or iTunes Store - Apple Support

If you get no help, contact iTunes Store Support and explain your problem. Fill out and send them this form:

iTunes Store - Contact Us - Apple Support

Regards

Giulio

Hello Christy,

Have you tried first topping up your iTunes credit, and then purchase the application? If so, please contact Apple. If not;

1. Go to the App Store
2. On the tab 'Today', go to your profile by tapping on the icon top right.
3. Tap on your name (Verify if asked for)
4. Then tap 'add funds to your Apple ID' or 'Top up Apple ID'

I hope this helps you,

Arjan

Same with me lol