Ask the local building official if there is a state home improvement law that applies to your project. Make sure the contractor complied with all state laws and is properly licensed. If not, he will have trouble defending himself in court. In some states there is a pool made up of the home improvement license fees that could help reimburse you for you loss if fraud was involved.

I would be cautious about trying to punish him yourself. Two wrongs don't make a right ... but three lefts do.

You could also contact:
Office of the Attorney General
Consumer Protection Division/010
P. O. Box 12548
Austin, Texas 78711-2548

A family member of mine was ripped off/scammed for a total of $77K by an unethical, slime ball contractor who took her money and moved to another state without doing the work he was hired to do. The police found him in another state, he was taken to court, and prosecuted with a third degree felony. 5 years later, my family member was only able to recoup $20K - and kept him out of jail with the hope that she would get her money back. She recently hired a private attorney, filed a judgement against him, and hopes to get more money from him this way. It's a bad situation all around.

You absolutely need to go the legal route. See if you can get an attorney through your local court system. That way, you won't have to hire a private attorney initially. You may have to do so later, though.

In hindsight, if my family member had done her due diligence, she would not have hired this particular contractor.

Good Luck!