Phone still not repaired and bad service!

I upgraded to a Sony Xperia Z3 at the beginning of Feb 2015. I had the phone for a month when I realized that a certain part of the touch screen is unresponsive. I did not drop or damage the phone in any way and then proceeded to return the phone to the Vodacom shop I received it at. It was the Vodashop at Mall @ Carnival in Gauteng. My Sony was at repairs for almost 3 weeks. When I finally got it back I checked if the problem had been fixed right there in the shop and it hadn't. The phone was still not fixed. When I got my phone back no further assistance was offered to me, as matter of fact I stood in the shop for about 20 minutes before someone assisted me. I was then told to hand my phone in at a repairs shop in Lakeside mall, because they did not understand what the problem was when I explained it the first time. Now I'm going to be without a phone that I'm paying a lot of money for AGAIN, because someone didn't understand me the first time. Unacceptable!