Bad Service

Bought a computer from Matrix Roodepoort in May 2015. It worked fine fir about 2 months. Then it started switching itself off while I was working. After a few times, the screen message said BLUE SCREEN. I took it back to Matrix and was told I had to pay for the testing. I refused and my own computer consultant re-loaded all my programs. It worked for about 2 weeks and then started doing the same, I took it back to Matrix and they agreed it was a hardware problem. After two weeks they called and told me to collect the computer. THEY CLEANED IT AND IT WAS BECAUSE OF STATIC!!!. I was furious. Now after a week it died on me again. You can hear the fan running and trying to start up again, to no avail. I have to hand in Tax returns for clients by the end of the month. I cannot wait another two weeks again. This computer is faulty. Please Help!