debt buyer deceptive letter

Hi all, I'm new to the group and have a situation that I hope I can get some advice on. I had an unsecured loc with HFC that following some issues wound up in default and eventually charged off. Although already charged off, I was working with HFC to pay an agreed upon settlement and ran out of time(I am disabled and unemployed following a serious accident). I had a balance of $1,500 left on settlement. I recently received a letter from HFC dated 1/26/11 stating that my account had been "sold, transferred and assigned" to S&P Asset LLC. I then received a letter from Stellar Recovery(same address as S&P) dated 1/27/11, stating that they had been "retained" by above mentioned creditor(HFC) to "present this claim on their behalf " the letter went on to offer a "settlement" of $4,800. Does this constitute deception on Stellar's part? HFC's letter clearly stated that they had sold my account to S&P and to make all payments and direct all correspondence to S&P on 1/26, but Stellar's letter on 1/27 stated clearly that they were "retained" by HFC to present a claim on "their behalf". Can I sue Stellar/S&P for this deception? The letter is obviously a form letter that does not apply to this situation, but can they be held accountable for this inaccuracy/deceit? I am prepared to pay my balance of $1,500, however, I will pin these bloodsuckers to the wall if they have stepped out of line. Despite my situaton, this is my ONLY delinquent account. I have drafted a validation letter and am well within the 30 day window to send. Any input on how to proceed would be greatly appreciated. Thanks!