Unhappy customer (Game Mthatha Plaza)

I was at game on the 27th during the half way sale in Mthatha, the shop was not fully prepared for the promotion as a result a store attendant gave the an incorrect heater that was an Alva not in the promotion but she stated it is… I have paid R1300 for this gas heater when I wanted the one that was R999 they refused to assist me with an exchange claiming I had already left the store and the don’t exchange or refund pay just now purchases