Although I'm ready to help users in any regard, helping with credit card problems is beyond my developer's abilities I'm afraid.

If your credit card is not accepted in online stores, the usual reason is your credit history. But it can also be something simple, such as a wrong address on the credit card. If you can't imagine any reason, contact the store, and also contact your credit card company - maybe they know something that you didn't know.

If your credit card is rejected, Paypal is likely not accepted either, but you can also pay with different methods, such as cheque. If the store permanently refuses your payment, but you need the software urgently, contact Support - they'll find a solution.