unsolicited calls

after time and time again of telling these ADT appointment call center agents to never call me again they kept calling and even on the day i had a home emergency happening i told the agent i am really busy in an emergency situation and cant talk now she kept trying to see when she can call back till i asked for a manager who then assured me i will be on a DNC(do not call) list and i was happy however shortly after i was called many times again and due to the situation at the time i was not able to give them a piece of my mind however i kept saying please don't call me again, so again yesterday 7th June 2015 i was called again and when i asked for a manager i got through to lisa engelbregh again and she said again i assure we will take u off the list, i asked what kind of system they use because taking me off the list didn't work before and she said they were not using any system they were just calling out of the phone book!!! how now would she put me on a do not call list??? when i asked she said she will tell some other head office or branch or supplier to tear the page that had my number on off allll the directories that they would get, who believes that..?