Claims I owe a deb of $1506.20 with Cascade Capital LLC...never heard of such a thing Renton Washington

I received a letter from Convergent Oussourcing, Inc. located at 800 SW 39th St. in Renton, Washington. I am being accused by a creditor called Cascade Capital LLC with a Client account #10218522453 and Convergent Account # S-43888111 with the name of the Original Creditor left blank, the amount they say I owe is $1502.20 and they are willing to settle for $527.17, let me just say that I owe nothing of the sort, this is felonious, bogus and trumped up charges. I've never heard of any of these people and I believe this is surely a scam.