unhappy client monthly my payments are good but fixing my problem last on the list

I had a very bad experience with the repair done on my cellphone. I booked my device in on the 02.10.2017 an only received it today. However when i got home an placed sim in to get phone up and running it did the same thing just worst. If I should have the phone in a charge now it will blow up that is how warm it went as the battery is running down. I find it totally unacceptable that MTN states that they have no say in the manner how repairs are done and that the under writer of the insurance company deals with everything. When I opened the contract and took out the insurance no-one told me about all this. I am in Port Elizabeth an they have no office local that I can go to this is utterly wrong.Monthly my payments are all good smiling to the bank but to keep me happy as a loyal client is last on the list. I have never had such bad experience like with this claim. I don't want to hear that the phone has to go into repairs again I want a solution to my problem ASAP as no-one on your board will expect to be treated like this when they have a problem