Makro bad service and returns

I bought an Alva outdoor freestanding canister heater on 27/06/2022. The heater has malfunctioned after changing the canister. I'm at the shop to return the item and Daphney at the returns office tells me I cannot my money back and that I have to wait upto 6 weeks to have the item checked out and repaired. Is this fair? I want my money back. In 6 weeks winter will be over and I have a 2 year old baby.