Our ceiling fell due to water dripping from an attic HVAC unit installation gone bad, and the house is covered in dust and insulation now. Advice on how to handle? The company who installed is coming to clean today.

It was installed back in July, just after the 4th. It was done horribly, with several repeat visits necessary to fix various problems, the last of which being a leak that caused our ceiling below to bubble and sag. They claimed they were ordering a new part and would be back this week to fix while it dried (the water seemed to be falling into the pan at a low rate), but there was clearly another leak we didn't know about. This am at 6, it fell and my upstairs hallway and loft, switchback staircase (all rug), and downstairs hallway and foyer/living room, are covered in dust and insulation.

He says he's never dealt with this type of thing before, so he's sending a drywall person to fix, and the same guy is going to clean it, too. I want to know, if anyone is willing, advice on what to ask with regard to safety, ensuring it's done right, insulation danger, etc.

[Here] (http://imgur.com/gallery/rmWGT) are images.

EDIT: On advice from a friend, I reached out to my home warranty company. Don't know why I didn't think of this before, since they're the ones who originally put me in touch with him. They have agreed that this was negligent and that dealing with his insurance is best for the damages, but he's coming today to look at what is causing the leak. Am I stuck with him performing the fixes from here on out? The warranty company says that this is the case. Anyone have experience even remotely similar?