I agree with Jason, stop the work, document all work, all written correspondence, do not let them on your property again, no changes, no promises, no work. Do not pay any money.
You need another contractor and you need to write out the work order, make sure all are on same page.
I have gone in after a bad contractor and I have been made to feel like I would do like the first. This is very uncomfortable feeling. Find a new contractor and get referals and make sure that you feel good about this person.
Then once settled on one, take the bad taste from your mouth and make this one feel welcomed and undertanding of your first experience.
Many customers feel good about the new contractor only to find out that this person you did ALL this talking to is not on the job. So, ask this question: Will you be on the site from begin to finish?
Now, the judicial process will take many many months and chances are, you will not get any judgement on the case. It will probably cost you more money also. Consider re grouping, cutting your loses, and begin again.
I took a lady to court due to insuf check on a large job. It took me 8 months to get before a judge, then the judge stated that she could pay alittle here and a little there, but steady monthly payments. She stopped again after about four months.
I wrote off the debt and dusted my pants and moved on.