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If you feel like you have done everything within your power to try and get the links removed, but there's just no way, then you should disavow the URL or domain.  You should attempt to reach the owners of the domain 2-3 times before giving up.  During my link removals, there have been a decent number of webmasters that finally responded on my 2nd or 3rd attempt. As for disavowing URL or domain, if the entire domain is something you'd never want a link from, disavow the entire domain.  Even if you only have ONE link from the entire site.  Still, disavow the domain.  Only disavow the URL if you think the site in general is good quality but you happen to be on 1 particular spammy page for some reason.