I have found some one build a lot of pbns(domains are aged and related with the kw), and sale a lot of links to my competitors. and my competitors get good ranks after they bought them. I can be 100% sure that my competitors have purchased the link. Because I use ahrefs, moz and other tools to check the competitors sites and found the new links from these pbns. And the maker of pbn also contacted me and asked if I needed to buy his link.
I do not want to buy these links, is there are other solutions?