Impossible to cancel

CARTRACK must be a **** to watch out for. I've been trying since January 2023 to cancel my contract, but they make it impossible for you. None of my emails or phone calls to them are recognized and they keep billing me every month. There is no consistency in staff who is dealing with my contract, so every time I try to get hold of someone, it is a new person who does not know my problem. My emails are simply shoved as 'being sent to the wrong department'. My only solution now is to change my banking account to stop the debit orders! Can someone help me? Should I go to the ombudsman?