You could always go through the hassle of prosecuting them.

My wife got ripped off by someone on Ebay who, as it turned out, was on 10 years probation for mail fraud (!)

A bunch of people who had been ripped off started e-mailing each other, and finally someone found the name of the offending seller's probation officer.

Quoting the name of the seller's probation officer (to the seller, in an e-mail) suddenly got lots more results than all the threatening e-mails to date.

__________________
Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic