Altech Netstar
Over a year and still no refund for cancellation

I sold my car in Dec 2011. I cancelled my netstar tracker as I no longer had a car and the contract I was on was a month by month. The following 4 months I was still charged a monthly premium despite my complaints.
They have still not sorted the error out and one of the payment that bounced as I requested it be stopped has been handed over.

This is not acceptable and I want this issue sorted. Customer service is not up to standard.