I'm selling media on ebay. I just got a message from a ebay member. He says if I don't take down my listing he'll report me. I haven't ever sold this particular product.
I just opened this account yesterday.
The complete step-by-step guide to get back to selling today!
I would just reply to them and let them know that you are not ending your listing. If they keep bothering you then I would set up some stealth accounts and buy stuff from them and then leave negative feedback for them!
I have felt for a while now that Ebay is like a "Members Only Club"
With that being said, If the other Ebay user is Strictly a Buyer or a Powerseller they could make life miserable for you, reguardless if the item is Legit or Not.
I have personally been though this type of thing MANY times, and in MANY different forms.