earlpearl - 12:37 am on Oct 14, 2010 (gmt 0)
Customer service for problems associated with Google Places is very poor. There is a way to possibly get some attention, though. Go into the Google Places Forum and add a message about this issue, specifically that negative reviews were placed followed by an extortion offer. Extortion is against the law.
Find threads in the Google Places forum where there are discussions about problems with attack reviews. Publish in those threads. Find posts in the forum where people have complained about the same thing. Contact those posters and see if they'll join you in a thread.
When an issue becomes large within the Google Places Forum it attracts the attention of the personnel that police it and tends to have a better chance at getting an action by Google. Above all, good luck.