How do I deal with an Online Yellow Pages Scam?

OYP contacted me at my workplace months ago. They seemed valid. The man told me that he was simply updating our current listing and they were recording this for quality assurance, blah blah. I made it clear that was fine, and we did NOT want any enhanced services, so do NOT add those.He said he would not. The... show more OYP contacted me at my workplace months ago. They seemed valid. The man told me that he was simply updating our current listing and they were recording this for quality assurance, blah blah. I made it clear that was fine, and we did NOT want any enhanced services, so do NOT add those.He said he would not. The "collections" department from OYP group calls a month later, saying we needed to pay a few hundred dollars.What? They produced a recording they pieced together with me saying "yes" to other things to this enhanced survey which I SAID I did not want, funny how the recording did not get that! Anyway they NEVER sent us a bill, and they claim they did. They also keep calling. I googled "OYP Group Complaints" and apparently they pull this all the time and actually they cannot ruin our credit or anything, but they do keep calling people and harrassing. What to do? I just wrote a letter to the scam artists saying "cancel whatever you signed us up for but did NOT ask for".