Convergent Outsourcing Collection Houston, Texas

I am pretty sure that I was just ripped off by Convergent Outsourcing.  Received a letter stating that I owed a little over $1300 and they would settle it for close to $500.  I have never heard of LVNV Funding LLC and have never had a Sears card.  I have been working on my credit for a little over a year and told her I have credit reports from the last 3 years and not once has any of these companies showed up on my credit report.  The rep was really friendly and said that she would make a one time offer of $300 to settle, but I had to do it "right now" or else I would have to pay the entire amount.  I would not agree that it was my debt (because it isn't) but she then told me that it would start showing on my credit report if sold to another credit agency and I would be "playing russian roulette" with my credit score.  Finally, I agreed to pay the $300, but still won't agree that it is my bill.  When I asked for proof, she said that it would take 30-60 days and by then my bill could be even higher with no chance of settlement because of the trouble I would have put them through.  Crap... I think I really messed up because I don't have the money to throw away like that.