Horrible Experience With MTN South Africa

Extremely unhappy with MTN South Africa. My Apple iPhone stopped charging and I took it in for repairs AT THE BEGINNING OF DECEMBER. The phone is still under warranty, so the gentleman that works in the MTN store in Middelburg informed me that the phone will only be looked at in January, as the companies close over the holiday season. Which I was fine with. Middle January, still no communication from MTN, I asked my father to pop into MTN in Middelburg, as you can't call the stores, and I work in Pretoria. They then informed me the phone is back and repaired, we can pick it up. Then when we got the phone it wasn't fixed, no report, nothing included, so they sent it back! I then got a call that I had to disable Find My Phone App on iPhone, I removed the phone from my apple account, then they said no it's wrong, (trying to blame shift, as it's now my fault that they can't fix the phone). I at least expected someone to call/email with instructions on how to deactivate it properly. So once again I went into an MTN store (two weeks ago) and the guy working there assisted me to disable the Find My Phone app... and to NO SURPRISE still, no one has contacted me... I wrote an email to their complaints department, no one got back to me, I then left a comment on one of their Facebook ads, and sent them an inbox message. They got back to me last night saying the phone was sent back again because the Find my Phone app is still active. How can this be after I went instore again to have one of MTNs people deactivate it? So now I wish to terminate my contract with MTN after 15 years, as they are not complying with their side of the contract.