As mentioned, I hope that you are a member of ATPE or the like. This is honestly the only reason I ever joined was for the legal protection. Only had to use them a few times, but believe me - a cease and desist letter from a lawyer goes a long way toward shutting that crap down. You will probably never hear from them again.

Since you are asking here, I am guessing you are not set up with one of the organizations. As someone else mentioned, you can't get retroactive help. Find a firm that will have a free initial consult and find out what it will cost to do a cease and desist. And next year, join ATPE or one of the others!