I would also report them to eBay for having false or missing contact information

"Falsifying or omitting contact information such as a member’s name, address, and/or telephone number when registering on eBay is not permitted. It is also not permitted to use fax or disconnected numbers as a telephone number.

If you believe an eBay member is using false contact information, please report it using the Customer Support link at the bottom of this page."

The report link is below:

http://contact.ebay.com.au/ws/eBayISAPI.dll?ContactUs&wftype=2005&rcode=IV%25P10054&subject=False or...

At a minimum it may serve to put a flag on their account (though one can only live in hope)