Negotiating a charge off?

I was contact by a collections agency. I worked out a deal to pay it off, but now I'm questioning if I'm being "scammed" out of money I don't have. I am getting a personal loan from family member to pay them. Otherwise they would take me to court for $5000 (which is 80% of my current annual income) The initial debt was $1200 (which went into defualt after losing my job 2 years ago). After being sold to a collections, it went up to $2390. I was contacted saying I owed $2315, a different amount then stated on my credit report. They dropped it down several hundred, but it's still an additional $400 in addition to the original 1200. I was charged by Edison Park for the initial payment, the collection agency on my report is CTR. Also I was told I would receive a letter saying it would be marked paid in full on my report. I've made one payment, another is due tomorrow, and the final payment is due in a week. Should I be concerned of any fraud they might be trying to pull or possible false information given?