2nd mortgage charge off & company (Wilshire Credit) has since gone out of business...

So my 2nd mortgage was charged off a few years ago, we stopped paying sometime in 2006. The company, Wilshire Credit Corp, has since gone under and is no longer in business. A year and a half (or so) ago, I started receiving letters from a CA with settlement offers, I contacted the CA in an attempt to settle the debt at the offer (just over 10% of the original debt) they listed on the letter, I did not provide my banking information and after verbally agreeing to an amount with one of their representatives I went about putting the cash together. After several days with nothing in writing from them, I contacted the CA again and was informed that they would not honor the amount the CA representative and I had discussed, and they then countered with an amount more than twice what was originally discussed. I declined and have since stopped contact with the CA. My first mortgage is current, my home value is less than half what we purchased for (like everyone else these days, I suppose) and the letters from the CA continue to be mailed regularly, although these days the settlement amounts are much higher...the original loan was $30000 and some change, the settlement amounts coming in now are closer to $20000 as opposed to the $4000ish that was discussed early in 2011...I have cleaned up everything else on our credit except for this ONE thing and it is SINKING our credit score. I am tired of spinning my wheels and was wondering if anyone could give me some advice on how to handle the CA and their bait & switch settlement offers. Should I send a letter to validate the debt, ask for all the paperwork, etc?? As I said before, the original lender is now out of business and the they charged off the loan long before the the CA purchased it and picked it up...I want to resolve, but was def frustrated by their actions. Any help or advice would be appreciated...Thank you!