Received used airtime voucher and cannot get help.

I bought R570 MTN airtime voucher, they sent me the codes and all codes said used when I tried to redeem them. I tried several times it said used but I didn't use them and no airtime was loaded on my account. I called them takealot customer service and they escalated the matter to the department. I received an email saying "sorry that you are getting an error, maybe someone else who has an access used the voucher before you"... I emphasized that I'm the only one who has access to the account and I know I didn't use them before. Now they stopped responding. I lost my R570 in that manner. This is not professional, they did not even bother to check the vouchers when were they redeemed and when did I receive them cos that was gonna help them solve the case. But no one cared I just had to lose my money spent on the airtime. I will never again buy anything from takealot.