Despite the low price offer via the telephone advertisment blitz, when the workers arrived, the price climbed threefold from about $120 to nearly $400. (The $120 is just for blowing dirt etc from the vents/ducts/pipes, which they did, but then to get this dirt out the core/central furnance, they wanted alot more $ to get the dirt out. ) Also, the hole they cut in the main outflow, to attach their large vaccuum hose, to was not properly sealed and ended up bending the aluminum frame - hence it leaked until I had it fixed properly. Since Blackwell came, my furnance 'pops' when the furnance turns on and off due to the metal expansion from the air flow/force. There was also still a good deal of dirt visible sawdust/dirt flying through. I called them many times over the course of 4 months at both the Scarborough office and also asked for help from the Ajax/Oshawa office, requesting it be done again, but no one would call back. The Scarborough boss was not returning calls, (apparently on vacation for some time) and I was able to track down the area manager, who agreed to come back and 'redo it himself' but upon setting the appointment they failed to show. Their 'no show' happened twice despite their promised. Never, never use this service. The invoice says work is guaranteed which is an outright misrepresentation. They took the money and ran and really didnt care about fixing a problem they created.