Bad service at Pick n Win

My mother went to Pick n Win Isipingo Durban to purchase some groceries, she lost a slip on the way out than the security took her goods because there was no slip.we went to manager to report the matter than the manager told us that she can't do anything as they will not check the till slip from the cashier and they also refused to check the cameras.Likely we found a slip after a long search. That was the worst treatment we received in that Store got a poor management stuff. There's need to deal with such bad service to customers.