Blocking someone in htaccess

[oracle765]

## STOP REFERRER SPAM
RewriteCond %{HTTP_REFERER} semalt\.com [NC,OR]
RewriteCond %{HTTP_REFERER} best-seo-offer\.com [NC,OR]
RewriteCond %{HTTP_REFERER} videos-for-your-business\.com [NC,OR]
RewriteCond %{HTTP_REFERER} semaltmedia\.com [NC,OR]
RewriteCond %{HTTP_REFERER} best-seo-solution\.com
RewriteRule .* - [F]

Hi Professionals I am after a bit of advice on apache

 

I have a regular visitor from 1999521.videos-for-your-business.com/ and I am aware this is spam from semalt.com, the trouble is I have tried blocking this but it keeps coming back the number 1999521 changes frequently

 

 

I have the following in my htaccess file

 

 

Any ideas what I could do

 

Thanks

Alan