It works. I successfully settled with a telemarketer for $300. Suntasia out in Florida. I'm in Arizona. They later got raided by the feds.
You have to tell them not to call you, document every call they make to you and track them down. I managed to find Suntasia's lawyer and got the ball rolling. They hired a local firm so I made it a point to divide responses between the states to waste their time and money.
After they gave me $300 I told the lawyer that I really didn't care who got their money, I was happy that the lawyer made some money as well. I didn't hire a lawyer. I think it cost a few bucks to file. So basically they probably spent 3-4 hours of their money on very expensive lawyers and lost.
You have to read the telemarketing laws and match up your documentation with the laws they broke and then file the paperwork and follow through.
It takes awhile and they'll fight it but you just have to stick with it until they cry uncle.