Top of the line Russel Hobbs fireplace heater is useless

I purchased the alleged top-of-the line Russel Hobbs fireplace heater - double the price of other gas heaters but it has been problematic from day-1. After a few days of use the heater refused to ignite. I contacted Russel Hobbs and the person I spoke with said it was most probably the oxygen safety system so I must open my windows and doors. What's the point of having a heater if we must open our windows and doors in the middle of winter!? But anyway, I open my doors and windows, and the heater refuses to ignite over a few days. The heater was collected for 'inspection' and I was told "it's working fine with us". I then asked them if it's possible that the oxygen depletion system (ODS) may be faulty as it refused to work for me over a few days and nights with windows open? They agreed and said they will now send it to their service department. I was without a heater for nearly 2 weeks as it took a few days to be collected and then it sat at Russel Hobbs for a few days before being sent to the service department where it sat for a few more days. I received the heater back on July 11th (with no explanation of what the fault was) - today - three weeks later, it has started to cut out every 15 minutes, whether I have doors and windows open or not. It will ignite but the heater stays on for just 10-15 minutes and then goes off. I contact the service centre and the person I was dealing with, Camlene, has resigned and the other person I spoke with doesn't seem interested in my heater problem – their solution is that I must bring the heater to them for repairs AGAIN! It’s one of the coldest winters we have had, we are contending with load-shedding (so we need the gas heater!!) and we must now sit for another 2 weeks without a heater while they inspect the heater AGAIN. I can see this going on for the whole of winter. I should have just bought a cheap Goldair or Alva gas heater – I’m sure they would have worked better than this Russel Hobbs dud.