Un-authorised Deduction

I sold my car on 15 Oct 2022 and notified Beame Car Tracker immediately. ever since I have been billed on the monthly basis despite the fact that my account is closed. I have emailed the company many time with NO success and they are still deducting the monthly fee from my account. Every time I ask the bank to reverse I am being charged a fee. do not Know what else to do.