We basically washed our hands of Polytech (Stop 6, we wouldn't even touch). 

All switch-plates and sockets should be clean of dust and should contain working bulbs.HEATING DUCTS AND PANELS should be free of dust and washed clean.WINDOWS must be cleaned inside and free of dust and debris.

Friends experienced a similar occurrence with their new build up here last year.The home was not heated during construction but the dishwasher & washing machine had been hooked up & tested during the warmer days.

We moved into our current home almost 2 years ago and had the washing machine worked on twice in the first 12 months.  

If you don't, you need to keep a lid on things i.e. water saving toilets, landlord thermostats, keeping a close eye if tenants are having several other people live there, car washing services on premises, etc.In the end, it all depends on how it cash flows and your tolerance.

I would ask what was he thinking of doing first and now what has he added to the Job.I would then, as other people have suggested call in other contractors.  

My main concern was he wasn't licensed for plumbing. 

I have 6 years experience in managing a construction company and two car washes.

Take that $500k plus my $250k down back and buy more.rinse wash repeat.yes, it's easier said then done.

Asking about the car they are washing, the mower they are using, just anything to start a conversation.