Worse ever security business in the history of service industries

I have had the most unpleasant experience with ADT Security. After purchasing a new home from the previous owners I inherited ADT as the security company until the last three months on the previous owners contract expired. New to the service, I renewed the contract to my shock and dismay. My alarm was frequently defective and eventually when it wouldn't arm I insisted they send a technician to fix it. After three weeks , the alarm was not fixed, in fact we had not even seen or heard from a technician. My house was defenseless all of December thus I decided to cancel my contract with ADT in January. I called in the cancellation, sent an email and got the cancellation reference via email and corresponded repeatedly with various consultants who called to confirm the cancellation. February they continued to debit my account, I complained to my bank and had it reversed and called ADT again to get their *********** accounts department to cancel the debit order instruction. Despite assurances that it is now done, March it occurred again and in April they put through a debit order for the equivalent of three months arrears. I am shocked and horrified that I entrusted my safety to such an competent company. I am now at the point of seeking legal advice.