MTN's preferred insurer seems to be *****ing iPhones

When purchasing my iPhone 6s at MTN at the V&A Waterfront, I chose to insure the iPhone with the MTN preferred supplier Pinnacle Marketing. I damaged my phone recently, made a claim and the phone was collected by Pinnacle Marketing. I was phoned and asked for the access code which they said they needed in order to test the phone. (Apple has since advised that this is not necessary). I followed up on the status of the phone and was told they were waiting for parts and to phone the next day. I did and was told that the phone was deemed 'beyond repair' and that a replacement phone would be sent to me. It was. I asked to have my old phone back. It wasn't returned to me. Yesterday, I had a message on my new phone that someone was trying to access my phone. I called Apple and after some investigation, they said there there'd been a security breach and blocked the phone. My phone is not used by anyone else, no one has my passwords and so it pointed to the insurer. I called them and they casually said 'Is someone fiddling with your phone?' I then received a mail saying that yes, the phone had been 'salvaged' (a nice word for ******) and that I should change the IMEI number and the iCloud settings. I spoke to Apple and they said this was a nonsense reply. It wasn't possible to change the IMEI and that it wasn't connected to iCloud anyway. I have asked to speak to a supervisor at Pinnacle, was sent a mail saying they'd forwarded my request and that a supervisor would call me. No one has called me. I asked for the supervisor's name. I haven't received it. I've phoned the MTN store and the MTN ********** 667 number a few times and I must say, no one is particularly bothered by the fact that YOUR PREFERRED INSURER SEEMS TO BE *****ING PHONES!!!!! Can you imagine giving your car in for repairs, handing over the keys and having your car ******? MTN suggested Pinnacle, I pay for insurance every month. I now have to wipe my phone and can't save anything on it and someone is able to access the information on my old phone. I've also been told by Pinnacle that they unfortunately cannot return the old phone. Of course not, it's been ******, but what about finding the culprit, an apology? Some sort of outrage and customer service? And why such a lacklustre response from MTN? You are my service provider and this is the insurer you suggested I use.