Cancelled account

My account was cancelled in 12 December 2013. ADT stopped debiting my account only in January. All of a sudden I get a call that I owe them for all the months that have passed since I cancelled. According to them I did not pay the 3 months before I cancelled. Why would I send a formal cancellation request if I was behind 3 months with my account. Why would they still be debiting my account if I have not paid them in 3 months?<br> <br> I am sorry ADT, I dont owe you anything and you will not get a cent out of me because you dont know how to do your admin.<br> <br> Please stop harassing me or we will need to sort this with the ombudsman.<br> <br> Ticket number: EC226A752C719<br> <br> With follow up email sent 08/01/2014 No response or reply received but debits stopped on the account.