Vehicle parts ****** at Panelbeaters

My car went in for a rear accident damage and on collection the front right lamp was malfunctioning and all four (4) tyres swapped. I have technical proof from Mercedes Benz that the control unit was swapped. Only MB approved technicians can do this and Sanrose is an MB approved panelbeater. They will not replace my control unit and tyres but they are prepared to "out of goodwill" reimburse me for the diagnosis. My insurance is not coming to the party though they sent me to Sanrose. The OSTI and MIOSA will as well not help since I want Sanrose to pay for the damages saying my request for assistance is out of their jurisdiction. Can somebody please help