Horrible service, I want my money back R1200

I'm so disappointed with Builders warehouseCenturion and their online service. I bought a gas heater and reported it. I mentioned that the heater shuts off after 2 hours and the other days it works. They told me that my gas bottle can be faulty. I've been using that gas bottleon my previous heater and stove. They don't want to take responsibility. They have to waste my gas for 2 hours to check if my gas bottle is working. How is that possible. Poor service and waste of money and my time. I have to go back to the house so that they can use my gas and how can lie and say that the gas is working whilst not. I'm ****ed off. I'm angry. They do not care. I wouldn't recommend anyone to buy a heater from Builders. Imagine it's cold so I have to stay in a cold house. They are going to benefit from my money.