If the domain information is fake, report it to ICANN and the registrar will have to take action.
http://wdprs.internic.net/
You have to explain to them why the information is wrong. In theory, the registrar is suppose to contact their client and ask them to put correct information, as incorrect information in the whois is basis enough for the domain to be cancelled.
You can also send DMCA notices to the registrar and host.