Tablet still faulty after taking it in twice

I have taken my Samsung Galaxy Tab 10.1 in twice now with an error I bought it with. When I goes to Edge/GPRS the screen starts flashing that you cannot use the Tab. At Vodaworld end 2014 (33.6km one way) they saw the error and reloaded the software and said to bring it back if it persists. The next time I took it to Menlyn (12.9km one way) they also saw the fault but said the couldn't repair it it had to be send to Vodaworld. When they said it was working we had to collect it from Vodaworld again. According to the technicians at Vodaworld there is no fault found when tested on 3g.(Come on guys the problem is only when it goes onto edge) I phoned the CEO's office but the guy there refuse to assist. he insist that I drive to Vodaworld again and return it once again. After driving 160.2km and it is still not fixed. I told this guy it is there turn to collect this tab and replacing it is what I require. He refused and said if I don't bring it in it will not be repaired. I wish I had the Cell C guys resources so I could place an add about Vodacom's lousy service on the first page of the paper.