Taking money from my account without authorisation

I cancelled my subscription with Cartrack in February 2015. Every month they run a debit against my account. Every time I phone they say that the info was sent to the accounts office and that they will pay the money into my account. Up to now no funds has been received. When I phone and ask to speak to a supervisor I am told that they will call me back, but they never call back. I feel that they are ignoring me on purpose. My next step is to go to Police and open a case of theft against Cartrack.