Dubious service.

I pay Cartracker on a monthly basis to track my vehicle in case it is ******. I have an app on my cell phone to check on it's location. I find that the car is not being tracked. When I ring them to check t he installation I am told that the device is out of it's warranty and I must pay R1000 to extend the warranty. How are they performing their duty under my contract with a defective device???