03-06-2009, 04:13 PM
There's no way to guarantee action from them, but I can make some suggestions.
First, send them a dollmail. Give them a reasonable amount of time(a few days at most), then if they fail to respond, send them another dollmail and inform them that you are trying to be polite, but if they fail to respond to you and your terms, that you will contact the owner of the site and have them punished for copyright infringement. If at that point they do not respond to that, leave a message on their profile telling them that you tried to be nice, but now you are reporting them for art theft.