R150 vouchers bot working

I have to say i was disappointed by african bank today. I was given a R150 voucher for using my card a certain number of times this month which i had to redeem at ShopRite / checkers. I tried to redeem the voucher a couple of times at shoprite and it did not go though. Imagine the disappointment, with people coming behind me. I had to take my mini grocery back to the shelves. If you going to offer something for free, atleast make sure it works. I do hope this is something the bank can sort out quickly as i see there are also a number of customers complaining about the same issue