Sasol Rewards not providing legit vouchers

I redeemed R100 in Sasol Rewards for a Spur voucher. A few minutes later I tried using it at Spur, but the manager came back and said the voucher is not working. He advised that it is probably too soon to be used (huh?). Anyway, a couple weeks later I tried again to use this voucher at another Spur, and again I was advised that it is an invalid voucher. Sasol Rewards are owing me R100 for providing me with a **** Spur voucher.