Seeking Advice - Someone Claiming © To My Sculpture

[almost-too-late.livejournal.com]

Hello! I have a quick situation I would really love to get advice on.

Some time ago I created a sculpture of a dragon jewelry box. I produced quite a few polyurethane casts of this box and sold them.

Now, it comes to my attention that there is an individual (not going to name any names for now) listing the boxes they purchased from me and saying that they're copyright them. I have attempted to contact this person however they are refusing to discuss the matter.

What are my options here? Can I DMCA them to have it taken down (they have pictures of the box listed) or is there a better option? This is highly frustrating to me, especially because they're trying to sell my boxes at a considerable markup from what they paid for them, from me.