I bought a heater on the 8th of June and after 2 weeks 1 bar stopped working

I bought a heater on the 8th of June and after 2 weeks 1 bar stopped working. I took it back on the 6th of July and was told that I cannot get a refund or exchange. The heater will be taken in for repairs with indefinite time on when can it be back. I spoke to the manager at the shop and he said if I'm not happy with that I must talk to the supplier of the heater. How must I talk to the supplier while I bought the heater at Dis-Chem? I called their customer service same day and till today I've never heard from them. And still have no heater in the middle of winter with a possibility of the it returning in summer.