very bad customer relations

I had a problem with a gas cylinder that I exchanged a mica Hardware, Morning Glen, Sandton. I took in the gas bottle after using it for approximately 5 hours for heating purposes. When I asked if the gas could be leaking, I was old that the heater must be faulty. An elderly gentleman helped me. He told me to fetch the heater and bring it in. In error I never got a slip for the gas bottle. As an old lady I took his word . I only managed to go back into the store 5 days later. I asked for my gas bottle and was told that they had no idea what i was talking about. They ten told me that they would have to check their cameras. I went in again and no one has checked their cameras. I was told there was a fault with the camera. This incident happened 3 weeks ago. No one has bothered to return my calls. I sent them an email on Tuesday of this week. I gave them until 5 p.m. yesterday 19/8/2022 failing which i would report them. They are basically calling me a *****. How people pray on the elderly. I have been buying in the store for 17 years Your help would be greatly appreciated. Many thanks. Lyn Cohen