How to prevent internet defamation about your forum?
 

A member had joined my site with the interest in spamming the site as an introductory post. The member was then directed to the FAQ section which clearly stated self promotion, links to sites, spamming is forbidden and members can lose membership access. The member argued repeatedly with the administrator, going in circles challenging the rules. Eventually the member was banned.

This person then went on to write a defamatory post about my site with the obvious intention of causing harm and discrediting my site. This person also went on to create their own forum on their site (the one they were originally posting in their introduction as spam) on the same subject matter. They also went so far as to rename their site to match the name of my site so it ranks high in google searches and to direct people interested in my site to their own. This in turn puts their site a few spots below mine in the google search ranks which opens up to their defamatory blog post about my site.

This person obviously feels burned for being banned for not getting their way in spamming on my site and for refusing to follow the site rules and has a vengeful spirit. Is there anything I can do about this situation?