Go here and find out who owns the domain:
http://www.betterwhois.com/
Then contact them with a certified letter and start calling the police and BBB in their city. If you paid through the mail call the post office and get contact info for the postal inspectors office and file charges of mail fraud.
This is a hard thing to stop, you just have to keep calling everybody you can think of and keep complaining until somebody gets tired of hearing about it. Also if you can find others who were ripped off by the same place get them to complain also. Local police tend to ignore this type of crime until they get many complaints. I went through a similar mess after being ripped off on Ebay along with a couple hundred other people.