These guys saved the day after another company (Company XXX) caused a big problem.
Basically, my condo building decided to hire a company to clean out all the dryer ducts in the building. The condo building got quotes from three companies. Company XXX was hired with a quote at $32 per unit. Anyways, rather than doing a proper job, they plugged the exhaust vent in my unit. (I think they tried to blow all the lint out the dryer exhaust hole but, in reality, the blowing just caused the lint to plug the exhaust hole.) All I can say is that your building should beware of going with the lowest quote.
Anyways, Company XXX wouldn't respond to my calls. I found City Duct Cleaning because they described the exact problem I was having on its website (the dryer exhaust was now going into my washroom because, since the exhaust hole out of the building was plugged, it had nowhere else to go but into my washroom). My building hired City Duct Cleaning and they fixed my problem.