This comp; is run by Ukrainian spammers and their pages are full of complaints but they keep on removing any negative feedbacks.
Just add the code to your htaccess file:
# block visitors referred from semalt.com
RewriteEngine on
RewriteCond %{HTTP_REFERER} semalt.com [NC]
RewriteRule .* - [F]
and
How to block semalt.com referrer traffic using .htaccess | logorrhoea.net