HAVE DEBITED MY ACCOUNT AND WILL NOT REFUND

I am at a loss as to where to begin.....I cancelled my service giving 1 months notice 14 months ago, the radio was collected by a Chubb staff member. I kept on getting statements, in July 2014 I emailed asking them to stop sending me the statements as my service had been cancelled. Then after a year I suddenly get debited without permission 2 months in a row, which resulted in my bank account going into deficit causing other debit orders to bounce thereby effecting a large fee that I have to pay for the bounced debits, not to mention the negative aspect that arises against my name on the credit bureau. I notified W Fortuin and copied I Pettiraj both in December 2104 and again in January 2015 - NO RESPONSE, I then phoned the accounts department last week and now have someone looking into this - but telling me that I need to give 1 months notice - clearly one division does not talk to the other.