Unsatisfied with my Vehicle

Unsatisfied with the outcome of my Vehicle. Car went into BLACK DIAMOND PANEL BEATERS for fire damaged 3 months ago , Miway said the car is repairable, since then it's been at their shop ... last month BLACK DIAMOND contacted us to say the vehicle is ready and they test drove it the day before, the next morning when I go to fetch my car and I test drive it the car doesnt move... a month later today the assessor, Coenie from MiWay called to say its a mechanical fault oil is pushing into the plugs and hence the vehicle cannot move and there is nothing they can do about it. After all this time from my car being ready to now being mechanical and technically saying it's my fault...what I'm failing to understand is the car was on the road moving when it caught alight after going into BLACK DIAMOND it's now mechanical... I have to ask myself is the insurance covering up for BLACK DIAMOND??? I WILL BE CANCELLING MY INSURANCE WITH MIWAY ONCE MY VEHICLE IS FINALLY GIVEN BACK TO ME!!!! PATHETIC SERVICE