Checkers Robbing customers

I went to Checkers in Northmead this morning. I had generated a R50 dstv rewards voucher using my dstv coins. When i went to pay i was told sorry if you use the voucher you can’t get discounted prices. The manager Eugene told me that there’s nothing that he can do about it. So i had to just accept to and pay. I lost put on around R25 of discounts which i find is unacceptable it’s not like checkers had given me that R50 voucher nor that checkers wasn’t getting refunded for that voucher. There’s no excuse for robbing customers