My orders keep getting cancelled. What can I do?

At first, my order was cancelled because of the credit card, at least that's what I understand from the cancellation email. So I thought I'm going to buy e-gift cards instead (1500 $ total) to redeem those in order to avoid that Credit card problem. But now my orders are still cancelled no matter what I try. I'm worried now that I won't get anything with those 1500 $ of gift cards. Maybe someone knows how this scenario can happen. I am very thankful for every advice.