First of all make sure you fill in all your account details on this page.
This is not an uncommon case, however not within our power.
Try the multiple Creditcard options the gateway offers. Try different cards.
If it does not work, you can pay with Bitcoin (or other cryptocurrency).
To use Bitcoin as method, you have to buy Bitcoin, buying bitcoin is simple.
We appreciate all crypto/Bitcoin payments, it allows us to keep going. You can find more information here.