Deny referrer via Htaccess not working

I’m getting a lot of traffic from some garbage spam website called getbottraffic4free.pw. Not even gonna visit that website to check out what’s up, I just want it gone. I found a way to block spam referrers using Htaccess and everyone seems to suggest the same solution yet I’m still getting traffic from this referrer.

I added the following lines to my .htaccess

RewriteEngine on
# Options +FollowSymlinks
RewriteCond %{HTTP_REFERER} getbottraffic4free\.pw [NC]
RewriteRule .* – [F]

Anyone any idea what I did wrong…?

The page I need help with: [log in to see the link]