Castle Maintenance Services

Have used Castle Maintenance for many years, with no questions or problems. This time one of the two guys suggested we have the B vent (from the furnace out through the roof) cleaned, as it had never been done. He informed me this was an additionally $100. OK let's do it, 10 minutes later he had done it, a total time for everything of 47 minutes. I decided to look on-line what cleaning the B vent incurs, at the minimum amount of time it should take 1+ hr (done properly). Now I am going to get an expert outfit with the relevant NADCA qualifications to come take a look, btw Castle Maintenance had never heard of National Air Duct Cleaners Association ???? Needless to say I want be using these people again.