Bad Service offer a coupon that can not be redeemed to clients no feedback

I made a first time purchase 3 December 2018 of R513.00 they offer a coupon code U3SP-K2WA-WSJC R150.00 OFF MY PURCHASE When I tried to Redeem my Coupon nothing happen I made numerous calls for help then Bantu Pasiya help me and said he is going to cancel the purchase and the put R513.00 credit in my Takealot account then he took me step by step through the system but then the message came up the coupon is only for first time purchase Well up to today numerous calls from my Telkom Account and 14 E-mails asking for help nobody came back to me to solve the problem and my R513.00 is still as a credit in my Takealot account Bad Bad Service If they offer a coupon the law is they must give it to a first purchase why do they offer it if we must go through all this complicated problems