misrepresentaion

I have managed to install a tracker upon purchasing my car. The first few months the device worked and I was impressed by the product, as the months went by I had an incident where they broke into my car a couple of items where taken including the car battery. From my understanding with the product in question I was suppose to receive a call from tracker to confirm if my car is still safe where I left it but I never received any call but then I thought service is running slow but,few month later I experienced an attempted hijack but managed to survive because of my cars anti- hijack system. I still didn't receive a call,then it clicked that the device might be faulty .i called tracker to notify them, I was told to get a new battery on the sensor device, did that still didn't work...someone was supposed to call me and find out if the device is still in working order. so I cancelled it and I'm still billed for a product that hardly worked...how fair is that...