Now days, it's companies like sothink who make this possible for hackers to simply download your .swf and de-compile as the hacker sees fit. Although I'm sure they market their software for "legal" purposes, it's just too easy do to.
If you haven't got any legal backing to your games or code, there's nothing much you can do unless you can prove it's your own game and code in the court of law. I'd send them a legal document (not in email, use postal mail to their firm) from your lawyer or someone legally representing you if anyone to completely take down this game from their servers or else face charges in the court of law which might result in their entire server being shut down to the public. This is called Infringement. Do you think they would risk running your "1" game on a website that most likely drives it's customers seeking online game usage from hundreds of games they have? Frankly, I don't think so.
Also, on this topic, if this has happened to you, I wonder how many other people they have ripped off. It might be in your best interest to do a little research on this firm before seeking any legal represtation so you can simply walk in and take them down based on your experience and most likely others just when the time is right!