Q: My credit card will not work on my iTunes

Contact iTunes support and ask them.

No one here could know.

Aug. 2015 topic on debit card not being accepted - https://discussions.apple.com/thread/7183022

Jul. 2016 topic on debit card not being accepted - https://discussions.apple.com/thread/7613365

If your credit card company‘s records don‘t match your records in the iTunes Store - http://support.apple.com/HT203208 see also tips in https://discussions.apple.com/thread/4245338

Long thread on security code error with some things that worked for some people - https://discussions.apple.com/thread/2045791

when i enter my security code for my credit card it says its invalid - https://discussions.apple.com/thread/3798384