Altech Netstar's bad service!!!

I bought a car in 2011 which was fitted with a tracking device as per insurance policy. I sold my car and cancelled my car insurance. I was not informed to also cancel with my tracking company. I received bills from Altech Netstar and I made two payments and cancelled immediately after. The payments that I made were not deducted from their statements and the bill just kept on increasing. I have sent them a number of emails but no response and I have made phone calls and every time I was promised that everything is sorted out. For the last few phone calls I have made recordings on my phone to proof that they don't to their job.