Trying to Cancel - Not so easy

I have been trying to cancel my service with ADT, but it seems like that is how they make money. They ignore any correspondence relating to cancellation and just keep taking money of my account. As anybody successfully ended ADT's service? I dont get service from them anyway, but as clockwork the money leaves my account. I have send mails. When I phone I am told to send a mail! An endless loop and the customer keeps on paying. On 2 October 2015 I sent a mail to cancel and I received an \acknowledgement"the same day to say that someone will contact me. Today I received EXACTLY the same mail. Playing for time and keep the customer paying. """