Wrong Debit

I had problems with this supplier ever since I sold the car that had their tracking device fitted. I did report them on Hello peter they said it was being sorted and even took the banking details of the new owner and emailed me the new updated information but still I get debited every month now I don't know what to do any advise would help. <br> <br> I'm really tired of this torture or ***** whatever it is I will never ever recommend this company to anyone even if I'm dead drunk. Please help anybody