Lawn Mower still same problem

I have bought my TrimTech lawn mower in December 2014. Hardly used it but it over heats, I took it back the 15 January 2015 telling them my lawn mower over heats. The sales person told me my lawn mower is working hard and it needs to rest. After I asked them if they are going to borrow me an lawn mower they said no. When i asked them what must I do in the mean time I got told that its not their problem.The sales person told me there is an cut off switch when I asked him to show me he didnt know where it sits. After sending it to Trim Tech three days later Makro phones me telling me I can come and collect it. They say its fixed. Well trying to cut grass with my Trim Tech 2200W it stops working I had to go take out my Ryobi 1200W to cut the grass finish. After an hour of cutting with my 1200W I test the 2200W then only it starts to works. I would like a new one or my money back.