iTunes keeps rejecting my credit card details it has taken before

Lately, on my new iPhone 6. The App Store keeps asking for my credit card details. It was the second time in a week I entered the same security code (as it asked) and now my phone won't allow any credit cards details on my phone. All I want to do is update something but all it says it says is, "These credit card details are invalid. Please enter a new credit card bellow." But the usual card that should work and has always worked will not work anymore and neither will two others I've tryed. All I want to do is update something. PLEASE HELP!!