False Advertising

Pick n Pay advertise that if you install the PicknPay Asap app you will receive R100 off your first order. I installed the App and placed an order and did not receive the said Gift, then I tried contacting the Customer Care Centre I was told since I had already placed an order, the R100 off fell away, I said that is false advertising. The person said, "well there is nothing I can do about that." I asked to speak to the Supervisor (they would not put me through) and was told that the R 100 would be credited to my account ...... Hello nothing happened