Assuming that your contractor continues to ignore you, then the next steps you could take might include:
Hire a lawyer to draft a letter stating your claims. Seeing your claims on the letterhead of a law firm might push the contractor to pay attention to you. I don't know the cost for this, but calling some lawyers will give you an idea.
Start the process of claiming your money back via the Wisconsin small claims court (I think that this will cost in the order of $100 to $200). You don't need a lawyer to do this. The process is designed so that you can do it yourself. I don't know if the court will award costs as well as the money your are owed.
Unfortunately the initial cost of either of those two steps is roughly about the amount of money that you are owed. The contractor may be relying on that fact to get away with stealing your money - as it costs just as much to get it back. But my gut feeling is to use the small claims court, as that will create a public paper trail leading back to the contractor. You could score a default judgement against them if they don't show up, however recovering that money is a different process (which I have no idea about)
However, if the contractor is doing this with no remorse, then it is likely that they have done it other people as well. So doing the Right Thing™ will benefit your community as well as you.