Disgusting attitude for a manager

I went to PnP-Bright Water Commons yesterday.I had received a mobile voucher from C***** that I could only redeem at a Pick n Pay.I got to the teller and explained that I would be paying with the mobile voucher.She advised that she did not know what I was referring to and that I should speak to the manager. The manager referred me to the manager who was on the floor (white female, healthy, black hair till her ears).I advised her that I received the mobile voucher and the teller needed assistance processing it.She rudely advised that if the voucher doesn't go through there is nothing she can do.I explained to her that the teller did not process the voucher as she does not know how which is why I was referred to her. She then advised that \they should know how to do it".She just stood there looking as stubborn as ever"