Paying for a tracker, without a car

In June this year I fitted a tracker on my car. Two weeks later on a Saturday(15/06/15) my brother and sister used my car to travel to their church in Mafikeng and they were due back on Sunday afternoon (16/06/16). On Monday morning, they still had not arrived and the cellphones were off so I called tracker to try and get the location of the car but they couldnt help me. The gentleman I spoke to explained how useless the tracker i had fitted in my car. We had to call all police stations from Mafikeng coming up to Johannesburg. <br> Tracker failed to track my car and family. On that Monday we learnt that my sister had died and my brother was in ICU. Tracker says I am bound by contract to keep on paying them because the unit installed was burnt as the car caught fire.<br> My car was written off and I'm being forced to pay Tracker although they failed to trace my car.