I suggest that the group buy admin to find another duct clean provider. It seems to me that the current provider does not know how to do their job. I had a bad experience about the duct cleaning provider from the group buy. They cancelled the appointment twice. First time they called me one and half hour after the appointment time and cancelled the appointment. They mentioned they were running late because of the wrong estimation. Then they made the appointment two weeks later. Half an hour before the appointment, they wanted to cancelled the appointment because the duct clean car is broken. First cancellation makes me think that they do not know what they are doing. Even they said themselves only do it as part time job. The second cancellation makes me think they do not have reliable equipment.
It is just my two cents about the current group buy duct clean provider.