Can't buy cartel coins

Hi!

I've been trying to buy a subscription and when that didn't work I tried to buy cartel coins from the site but I getting an error that there maybe a problem with my credit or debit details but its the same card I use on different sites. 

I don't have access to another card nor a paypal account and I've tried some of the tips that have helped others with the same issue but they haven't worked for me.

The only issue I think might be there is that my swtor account and ea account have the same email but different passwords and I can't find anywhere where they might be connected. Would I need to make a paypal account?

Any help would be very much appreciated.^^