I can't purchase anything from the itunes or app store.

It just says "Your Purchase could not be completed" and it happens on my iphone 5 and my recently bought macbook pro. They are both using the same acount. It wont let me purchase movies or albums or episodes, it only lets me purchase free or single songs. i dont know what to do can anyone help? I've tried re entering the credit card info and even entered a diffrent card. I think its only letting me purchase items up to a certain amount im not sure though.