Apparently, you don’t accept VISA credit cards. Because all of mine rejected from two different banks.
Please, solve this problem of mine @Team212
Or maybe your bank doesn’t support Merchant code used by T212? 
Yes that also a valid reason, tbh I ain’t expert on payment codes.
Although I have tried the two banks that I am using!
Well I am not sure T212 can help you with credit card rejected transactions. You should reach out to your CC issuer to check the reason.
Alternatively you can try to top up Revolut with your CC, then use Revolut to top up T212 acc.