Faulty heater

On 22 May I bought a Logic 3 Panel Gas Heater at Game, When I got it, it was not working, I sent it back to them, they told its taken for assessment. They dont call me for progress, I requested the refund so I can buy another heater the refused to refund me, I dont even know what is happening. This week is the worst, it is very cold, I can not get warm, the dont even bother to inform me what is going on. I am using a lot of airtime to follow up, sometimes they just transfer my calls to an unattended line. Iyoh I really need advise on what I must do. Any one who can assist me to either get a working heater or refund from Game please be kind to assist, or advise on what else can I do.