repair nor done

in November 2015 we bought movable air conditioner (DEFY) and in early December we returned the good because it was malfunctioning. the problem was/is that when you switch it on and you put it on cold, after sometime probably on the interval of between 10 to 30 minutes automatically, the air conditioner it switch it self to heat even though the light indicate for temperature is on cold but the condition that comes out is hot on those intervals. Meaning is cold /heat in those interval. therefore i send it for the repair and in Late December i received the sms to say the item is ready for collection and the problem is fixed. EVEN TODAY IS STILL DOES THE SAY PROBLEM. I bought something that i dont want. Our temperate is extremely hot and that the reason i wanted the air conditioner and i got the opposite of what i wanted. please help me.