Someone claims I own a small amount of money, and claims this is part of a contractual agreement. I can’t find the contract and asked for them to produce a copy of the contract bearing my signature as proof of their claim. I have asked for this 2x in writing by way of email. My email has been acknowledged 1x but they only reiterated that I'm obligated to honor the contract. So far they have not produced the contract.

What is the appropriate next step?

Thanks