Calling the "to be removed" number only puts you on more lists, it is a scam.
take revenge, post their telephone number on some not so reputbale websites offering anything from sex to free equipment, or some other outrageous "to good to be true" offer make sure to put in the ad that the caller needs to mention the key word "junk faxes" in order to get the deal, this will send a message. BE careful where you poost though, you do not want to get in trouble, go to a library or if computer savvy use a proxy. Time to fight fire with fire.