Damage to vehicle

I took my vehicle to Bosch service centre on Republic road, Ferndale, JHB to have it serviced. In addition to the service, I wanted them to check the clutch and brakes before going on holiday. The mechanic then took a drive with the car whith me as a passanger. The mechanic then made an accident with my car by driving into the back of another car. I got 2 quotes for the repairs but Bosch insisted I take it to their panelbeather which i did. Being uncomfortable to use their panelbeater I insisted they credit me with the amount their panelbeater quoted so that I can use this and pay in the difference to have my panelbeater to fix the car. The incident happened on 4 December 2018. They have been giving me the runaround until now with no commitment from their side. I'm the only one calling them to follow up and each time their is a different excuse.