Q: it wont accept my bank details

If you would like help from these user-to-user forums then you will need to provide more information than 'won't accept my details' e.g. what happens when you try to add it, if you are getting an error message then what does it say ?

If you are getting a message to contact iTunes Support then you can do so via this link and ask them why the message is appearing (we won't know why) : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption

If it's a different problem ... ?