Q: Have 50.00 credit in iTunes tried to use it and it says earlier credit card problems. I'm not using credit card . Instore credit

Hello, Rolandnrenee. 

Thank you for visiting Apple Support Communities.

If you are having issues redeeming an iTunes credit, here is an article that you may find helpful.  See the section labeled Contact iTunes Store Support.

If you can't redeem your iTunes Gift Card or code

http://support.apple.com/kb/HT6021

Cheers,

Jason H.