There are several things you can do, although it requires some continued work on your end. Documentation is the first step in the process. Initially you should take a screen shot of your work and the plagiarized work and place them in a word document. Be sure to also copy the URL of where your work was used without your permission.
The next step is finding out who owns the website where your work was used. You can do that through the WHOIS database. From there you can obtain the email information for who the website's host company is and also the webmaster. Contact them and inform them of the offense and request immediate removal. You can also go to the contact page of the company and contact them directly and request immediate removal.
Next contact search engines like Google and Yahoo to have the information removed. They will want a copy of your proof and that is where the word document comes in handy. You should also contact the FCC.
Lastly, you want to find an attorney who handles this type of case and obtain their advice. You may have a valid case and could recover financially.
If you submitted the work through a site like Elance or Odesk, they have an arbitration system that can help you with this type of situation as well.
I hope this helps!