Damaged Goods and Bad service

I purchased a Iphone6 via contract upgrade on the 1st of Feb at Westgate Mall. On the 14th of Feb the home button stopped working and I went o MTN in Festival Mall and they told me to go back to the exact MTN Store that I got the phone from. I don't stay in that area anymore. On Sunday the mobile phone just died, it went blank on me! I then went to MTN in Greenstone and they told me to send the phone myself to the repair center in Midrand. I believe the Phone is still under warranty and that there is some sort of factory fault. I am very unhappy as this phone is still new and I am being sent from pillar to post!!!! I even tried calling MTN Head office but I never get through. I just want this phone checked out and be given a new phone. I have been with MTN for a very long time and i have never been this unhappy with the service!!