Can a collection agency have the wrong amount?

i got a statement from a collection agency and they are trying to tell me I owe less that what I did when I initially defaulted on the loan. they are also willing to settle for half of that. I have full intentions on paying this. now, its not that I am complaining, I just do not want the balance difference to come back and...for lack of a better statement...bite me in the butt. I did call the original creditor and they confirmed that the debt has been "charged off," so I am assuming this is a legit statement from the collection agency. any input would be helpful.

Collection agencies buy charged off accounts from businesses for a fraction of what the debtor owes. Suppose that's ten percent. They could collect fifty percent and still make money. As long as you are sure it's OK with the business you originally owed the money to and have it in writing that it's "Paid in Full" you will be OK.

Also, be sure you have it in writing that in exchange for settling the account, the collection agency will remove all related negative marks from your credit report. Get this in writing before you make the payment, else you have no leverage and you have to wait for any negative marks to expire on their own. If they tell you they can't, they can. It's a very common negotiation.