Gas & More Kimberley

I bought a 9kg gas cylinder at Gas & More Kimberley on 20 June. I bought a gas heater the same day at a different store. I used the items for 5 days 2hours max per day. On 3 July the bottle was empty, phoned Gas & More and they said I must bring the bottle to be weighed. Took the bottle there, it was not weighed, a lady named Yolanda assisted me. She explained to me that with the heater a 9kg cylinder sometimes last only 3days. I explained to her I don't use it everyday and if I use it, I use it for 2hours max and on 1bar only. I told her it doesn't make sense to me, she insisted that a gas heater uses a lot of gas. I told her I understand what she's saying, but I'm not new to using gas cause I'm using a gas stove at home. I used this one at work so to me it just don't make sense for a 9kg to last 5 days if I only use it for 2hours on 1 bar and sometimes less than 2hours. She told me the heater might have a leak, told her it's brand new and if that was the case I would smell the gas, because I use the heater in a small room with a carpet. She offered to give me R40 discount if I refill the cylinder, I told her no I'm not happy with that. She then told me then she has to refund me R650 for the cylinder and that's what she did. I went back to the store I bought the heater from, they ensured me it's impossible for a 9kg cylinder to be empty if I used the way I explained I was using it. The guy told me at his previous office he used the heater with a 3kg cylinder daily for the whole day and it would last up to 2 weeks. I'm beyond dissapointed with the service I received at Gas & More.