All credit cards must support AVS(Address Verification System) in order to be accepted. Most international cards do not support AVS.
When a credit card is declined, the customer's bank will often times put a hold for the declined amount. This hold will disappear on its own, but may take up to 24-48 hours. If the customer needs to get rid of the hold before that time, they will need to contact their bank. There is nothing we can do on our end.
All PayPal payments must be made with a verified account. We can not ship any products until a verified payment is made.
If you have any other questions regarding payment feel free to email email@example.com.