3 Months later I don't have my and expected to pay 3200 for repairs

I am really not pleased with MTN repair services. I sent my phone to MTN Store Johannesburg CBD (Loveday) in July for repairs. There was no communication until I started to follow up with the late August and I was told my phone was taken to SONY for repairs, no one tells me that there are charges involved. Mid September still no feedback, I follow and I was told the phone is still in Pretoria and apparently they sent me a quote. I asked why do I need a quote when my phone is still under warranty? MTN moved their responsibility and now wanted me to follow up with SONY (SSS Cellular). I couldn't get hold of SSS Cellular, went to MTN and they told me they will get the quote, I got the quote today saying I have to pay 3200 to repair the phone. No way I am paying, that's like me buying a new phone. On top of that the store told me I would to pay 500 for delivery fee and 171 to cancel a quote. I am not paying anything for this. I want my phone back the way it was please!!!!!

I have tried to get MTN on Twitter to no response even today. The guys at MTN Store say they don't know what to do because Sony won't release the phone without a payment. One of the managers said I must follow up with Sony as it has nothing to do with the store. I took the phone to the store, I have contract with MTN not SONY, ITS NOW OCTOBER, PAYING MTN EVERY MONTH FOR A DEVICE I CANT EVEN USE? Is it actually possible to cancel this contract with mtn. I cant be paying month to be treated so badly :(