So I'm a PC player and wondering if there is some sort of work around to be able to use gift cards as payment for DC cash? There's no way to enter the info I've found to get it accepted
try to add yr card to CURVE app or open revolut account and top up it by gitft card - then buy mp cash (pm if y need promo codes )
I used prepaid VISA cards for the first several years of playing this game and never had an issue. Have you registered your card online with all the appropriate info? Most online purchases won't play nice until a card is registered. You could try adding your card to Steam and buying that way, I think that works, though I've never used it. As a last ditch effort you could try a support ticket or message Mepps but I'm not sure either of those options would get a result before the sale ends due to the holidays. Hope you get things sorted out.
If you have dcuo installed via steam you get the option to pay from your steam wallet. If steam accepts your prepaid visa that can be a workaround