Tracking device installation gone wrong

I had a Discovery Insure policy that I cancelled at the end of January 2015. As part of the policy, there's a tracking device installed in the vehicle and that must be removed on policy cancellation. Discovery scheduled for the removal of the device on the 25th Jan, sending a guy to do the work.<br> <br> On arrival, the guy was informed that he SHOULD NOT start the car as there was no oil in the vehicle, to which he agreed. The battery on the car was dead and I was happy that he would not be able to start it even if he wanted to. <br> <br> Against my wishes, the guy attempted to start the car. When he could not get it to start, he swapped the battery on my car, replacing it with the battery from his vehicle and proceeded to start it. This stunt has left me with damages to the engine estimated at R90 000. Discovery is not taking responsibility for this, neither does C-Track. In this case, whose fault is it?<br> <br> Surprisingly, the tracking unit is still in the vehicle. So not only did the guy not do what he came there to do, he caused damage to my car and no one wants to take responsibility for it.<br>