I think they call very often from the same company but providing different telephone numbers.
Call to Bell they explains how to trace caller number and report to the police these abusive calls.
I get 3 or 4 calls a day from a number that cannot be called back or traced to any company in particular. Based on the lag between us when I speak to these people and the person's thick accent which isn't very understandable, I'm sure the call is coming from somewhere in South East Asia....most likely India. After getting sick of getting no where I told them I am interested and would like to book an appointment. They then gave me this number, 647-656-5775 and told me their company is located in Scarborough, Toronto in the Victoria Park area. I called this number and the person I spoke to was Rick (clearly not his real name...unless it's short for Rickdeep...I'm am also brown, so no i'm not being racist lol) and he told me the company's name is Safeair Duct Cleaning (there is a facebook group by the same name...not sure if it is related...but can't be a coincidence).
After telling "Rick" that if I get another call regarding duct cleaning I will book the appointment and have the police at my house for when he shows up....he told me he has access to the server in india and will remove my number so I won't get another call. I told him I will be reporting him to the better business bureau and I reminded him what will happen if I get another call. He said removing my number was just a click away and I will not get another call.
I'm not sure if I am in the clear now, as this just happened, but will update in a few weeks when whether or not I've been removed will become clear.
Just an update: After about three weeks of not receiving any calls, I received another call regarding duct cleaning and in the message they left the same number: 647-656-5775 but a different name. This time the company the were calling on behalf was Toronto Duct Cleaning Service. I spoke to the same guy at that number this time but he said his name was Sean this time.
I am calling the National Do Not Call List again and making another complaint. Not sure if it will get me anywhere or make the calls stop but it's worth a shot.