2 faulty laptops in two years

I bought my first laptop in march 2013, a Lenovo (2g ram 500gb hard drive) for 4500 rands. It had a a lot of defects brought it back to them for repairs since I had a three year warranty with them. Brought it in for more than six times with different problems all the time until they told me that it was beyond repair and i should come and get another one or top up if the same laptop is not available. I topped up with 800 rands last year on 7 November and I got an acer aspire with the same specs as the previous laptop. When I got home (Zimbabwe) I realised that the unit had no sound , I immediately notified the customer care of the problem and explained to them that I could'nt travel back with the unit . Brought it in December as per our agreement on the phone and was told that they were closing for holidays and I should bring it back on the 5th of January 2015 which I did. Received it back with sound and it disappeared after two months, I thought it was a software problem tried fixing it but I did not have access to the master account as it belonged to someone else. I began searching the machine thoroughly, I found pictures of the previous owner. Now they want 1000 rands in repairs