Cancellation

I am acting on behalf of my elderly mother and cancelled our contract with ADT, simply because we were offered an "all round" package which includes a bicycle patrol and is just over half the price. At NO stage was I informed that the alarm system is on "rental" for the past 16 years plus. No one informed me that due to cancelation they would remove the alarm, and I spoke to a number of people during the process. I arranged a technician for yesterday to obtain the installation code (again they agreed to send one and no questions were asked) so that I can give it to the new security company, and an hour before he was to arrive, I got a phone call to say that he will no longer be coming and they will remove the entire alarm system. Firstly, surely after 16 plus years, the system is no longer rented and been paid for? Secondly, why do we need to pay for maintenance thereof if it is the property of ADT? Thirdly WHY DID NO-ONE tell me this? We are now sitting with no security. I need this matter sorted out URGENTLY please.