poor service

I took in my car for a loss in oil after a week I picked my car and noticed a lack in power so I drove immediately to smg rocks I spoke to the manager and I was told to leave the car there its been with them for 3months they opened the head and said all the bores where damaged and did a fault report. According to the report the warning light came on at 94800km mini smg says I drove the car while the light did come on and overheated which I did not do so I phoned smg to find out whats the mileage on my car at present t I me it was 94800 which clearly shows I dis not drive the car while the light came on my car was damaged by smg rocks and they ewfuse to repair my car