Dissatisfied with car track

Last year I bought a car and installed car tracking device from car track, Unfortunately this year February I was involved in a car accident and my car was written off by my insurance and didn't buy a new one. I informed car track about the accident. But they refused to cancel the debit order and instead they said I must pay a large amount for cancelation. I have been paying car track for 910 months now without a car. This I decided to reverse the debit order. But they keep harrowing me demanding a payment. Iam a pedestrian for heaven's sake, What Am I paying for. Iam expected to pay for a tracking device without a car for life.