The only website that I know you purchased a "dragon balls z" before is g2a.com so maybe this is the site you are looking for. Also, don't forget about "steam" they are also selling this game, but the problem right now they're no longer support Bitcoin as a payment method so I don't think you can ask for a refund from them since they no longer support Bitcoin.

Anyway, you can try contacting them and ask for a refund, but make sure that you can provide a proof that you purchased "dragon balls z" like transaction ID.