Tracker installation damaged my Car

On the 15th i sent my car (Micra Nissan) for a Tracker installation at Tracker in Durban. After the installation the car signaled that theres an error in the engine and its started jagging. Sent the car back and was advised to send it to Nissan of which they also advised that the tracker should be removed. After removal of the device the car is still faulty. I have phoned and spoke to several people at Tracker *Ashen, Solven Reddy* and still the matter is not resolved. Phoned the branch manager and he was not available and did not bother to call back. The car has been fixed at Nissan at the cost of R11 300 and Tracker is disputing their mistake. I am highly disappointed with their service and have appointed my lawyer to assist with the matter. Its been almost 2 weeks without my car and im furious. Such a bad experience