Ever gotten bill collector call from ';Ken Hughes';? How to deal with Merchants Credit Guide?

Just wondered if anyone else has dealt with this sleazy company, and if the results were good. I sent a letter certified telling them to validate my debt or cease and desist contacting me or pursuing the debt. Any other ideas from someone who's dealt with these people? I also don't talk to them on the phone, they are RUDE, RUDE, RUDE and you don't get anywhere.