Bad overall service

I took out a contract with MTN in May this year. The iPhone 6 gave me problems and I booked the phone in to have it checked out in September this year. They found no fault with the phone.<br> I could not make it to the store before 7 November and the telephone number does not work. The phone continues to ring with no answer at MTN Waterfront. For this reason, I could not inform them that I was not able to make it before this date.<br> MTN now refuse to check out my phone under the warranty. They gave me a bad phone, the screen is coming apart, this after they told me there is nothing wrong with the phone.