It says my Apple ID has been associated with too many credit cards

Multiple credit card changes are sometimes an indication of suspicious activity, so the account was locked for your protection.

You‘ll have to contact Apple directly.

iTunes Store official support (or start with the Contact Support link at the top-right of this page).

https://support.apple.com/itunes

Contact link for Apple ID security issues:

https://support.apple.com/en-us/HT204169