It is important to document cases like these, so others in the future won't panic when such SEO blackmail happens. The closest form I could find to report this

It is important to document cases like these, so others in the future won't panic when such SEO blackmail happens. The closest form I could find to report this to Google is: https://www.google.com/webmasters/tools/paidlinks https://www.google.com/webmasters/tools/paidlinks Though not regular selling links for money, I would make note about that in the additional details and provide a link to their XRumer domain list. In my experience the folks over at the webmaster forums: https://productforums.google.com/forum/#!forum/webmasters https://productforums.google.com/forum/#!forum/webmasters are good at, and interested in, handling these sorts of cases.