Debit Continues even after cancelling the account

I bought a 1.4 Chevrolet spark in Jun2015 and apparently my vehicle had a tracker, one which was supposedly installed by Netstar. On the 11Aug 2015 I was in a car accident and my car was written off. A few months thereafter I tried getting a hold of Altech Netstar to notify them of the incidents as I was aware that the debit order for the tracker still goes off. Firstly, its a struggle to speak to a consult, once they hear you mention anything about cancellations, they put you on hold. I was put on hold numerous times. the one guy (consultant) I spoke to said the people at cancellations are very busy, he will send them an email to proceed with the request to cancel my account, I asked him to Cc me on that email as proof that he really followed up, then he told be he cannot do that as its against their policy. I then started sending emails myself, I still have the follow up emails saved. I officially got an email back on the 12Jan2016 confirming cancellation, after several attempts. I asked them to pay me back all the money they have been debiting me for a tracker I did not own, but they wouldn't. I then tried to reverse the money back but could unfortunately only reverse for 1 mont