Q: Can't download Free apps w/out credit card??

The reason this is happening is because you have an unpaid balance on your account. To view your purchase history, follow this link: See your purchase history in the iTunes Store

You will have to pay the balance on your account. This is the reason why you have to enter a credit card for a free application because you owe money on your account. You will have to enter a new form of payment, OR purchase iTunes store credit and redeem it on your account to cover the cost. If you view your purchase history, you will see what is owed, and be able to edit your payment information.

When it says your card was declined its because your bank declined it. Consult your bank and ask the fraud department why they have declined the transactions. Please note that the bank does not tell the merchant why your card is declined.

Hope this helps!

The same thing happens to me and I DO NOT HAVE AN UNPAID balance. Sooo frustrating.

If you get a "problem with previous purchase" error, then you need to contact iTunes support to clear that up. http://www.apple.com/emea/support/itunes/contact.html