If you need to block a user agent / bot / browser from your site, you can do so with a .htaccess rewrite -- note this applies to apache web servers and nginx would have its own method.
RewriteEngine On
RewriteCond %{HTTP_USER_AGENT} botName [NC]
RewriteRule .* - [F,L]
Change "botName" to part of the user agent shown in access logs.