You can check who actually owns the domain here:
http://www.whois.com/whois/(just type the forum name into the first field and hit Search next to it)
After that, you could try looking up the company details in the Secretary of State business registry:
https://www.sos.ca.gov/business-programs/business-searchBut honestly, filing a complaint will probably be a waste of time. Maybe the only way to get through to them would be if they received a few thousand notices saying something like:
"Until Estée Lauder gets sorted out the way it used to be, we aren't showing up to the forum, we aren't clicking your ads, and you won't be making a dime off us."