Just use the plea of the debt being 'time barred" meaning it is beyond the statute of limitations to seek civil action.
If you have any paperwork that shows the last known date of delinquency, bring that with you to prove it is time barred.
Also have them provide proof they own the debt, if they are asking far more then what was owed then the following would apply
DEMANDING A LARGER PAYMENT THAN IS PERMITTED BY LAW: The FDCPA prohibits debt collectors from misrepresenting the character, amount, or legal status of a debt.
The types of complaints that fall in this category include, for example, allegations that a collector is attempting to collect either a debt the consumer does not owe at all or a debt larger than what the consumer actually owes. Section 807(2), 15 U.S.C. § 1692e(2).
and please do not believe that answer from the legal expert, that one is way out in left field.
Hope this answer is of help to you
LEGAL DISCLAIMER: The answer provided here is intended for informational purposes only. It is not intended nor presumed to be legal counsel or professional legal advice