Cash converters Sunninghill - bought defective gas heater but refuse with refund

I bought a gas heater by Sunninghill cash converters yesterday and it emits gas while on, which shows clearly that its defective. I have returned it for refund but the manager refuses to give me a refund. This is very frustrating because your policy states that I could either get it repaired, returned or a refund. I don't want the heater anymore - I need my money back. It doesn't make sense that I have to sell the heater back to the store at a loss if I don't want it when I bought it yesterday, it hasn't even been 24hrs since I bought.