First of all, there is no need for most casinos to scam people for vouchers, as it dramatically hurts their reputation; they earn more from the players than they would earn from the scams. Moreover, the vouchers are processed through Neosurf, and the company approves websites allowing them to receive and activate vouchers. It means in case of fraud, you will be able to contact Neosurf, and they will freeze the scammers' accounts and return your money.