CANCELLED 5 YEARS AGO - GETTING AN ARREARS BILL FROM DEC 2015

<p>I've tried contacting numerous numbers NOBODY CAN HELP ME. In 2011 I cancelled my ADT. Faxed them the cancellation letter. Moved to a different province. Sold my house last year February. Until two weeks ago I get a call from a rude agent my account in arrears????? Since Dec 2015????? I CALLED THEM BACK I WAS TOLD THEY UPGRADED THEIR SYSTEM IN DECEMBER..Friday received an SMS with outstanding amount of 1709. And my name will be listed on ITC???? The contact number I tried calling to no avail. Today I get told I must go find the cancellation letter??????? </p> <p> </p>