ADT debiting incorrect account for over 6 months

I have been notifying ADT of changes in my banking details since FEBRUARY. They keep debiting an old account which I have been trying to close but cannot until they change my debit order details.<br> Last month I even sent my mother to their offices (I live in a different town) because they clearly do not react to emails and phone calls. They gave her forms which a consulted emailed to me while she was there. I filled them out and returned them while she was there. This was on the 6 August 2015 so they had more than enough time to make these changes before they had to debit my account at the end of the month. What annoys me the most is that I am the one who endures the bank charges at the end of the day and the bank won't allow me to close that bank account until ADT stops debiting from it. <br> It's been 6 months!