Device not fixed and poor client service at MTN

I've been trying to have my device fixed since 12/03/2014 without success. After MTN made me pay for a new battery, the device was sent back for the 3'rd time, I received it back on 11/06/2015. I tested it at home and found that THE PROBLEM WASN\T FIXED. I took my device back to MTN Irene village mall today and an Afrikaans-speaking chap attended to my problem. He checked my device and decided himself that there is no problem with my device and that is only network coverage. Despite my solid counter-argument