Gas heater

I bought a gas heater at your East London store on 22 May. It stopped heating up, when I went to the store I was told I couldn't exchange it. My heater is at the store awaiting to go to the supplier and I'm sitting here without a heater that I paid for

Please make me understand why I'm unable to get a refund on my heater as I've had enough of this running around

.went to the store that took my heater and I couldn't even get proper feedback from the store manager. I have been calling since 13 June when my heater was taken in ,bear in mind I bought it on the 22 May it wasn't even a month old when it started to act up