Tracker do not cancel a vehicle when you sell it

I phoned on the 12th of January to inform Tracker that i have sold the vehicle and that the cover must be cancelled - as it makes sense not to pay for a tracking device on a car you no longer own...<br> I was promised an email was sent to the cancellation department to process the cancellation of the cover on the vehicle. En of January I got my invoice and still paying via debit order, for the car I sold. Phoned on 2 February to yet again ask for them to remove this vehicle - another email will be sent, I sad no as we have seen this route is not successfull so i am being transferred to the call centre - THEY DONT ANSWER THEIR CALLS. Called back and complained that i am not going to accept yet another confirmation about an email sent - as they dont do their work i want to speak to the department doing the cancellation or speak to customer service. Operator informed me I must come to their office if that is what i want to do - SO NOW I THE PAYING CUSTOMER MUST GO TO THEM TO PLEASE ASK THEM TO DO THEIR JOB!!!