This can be a common problem. Registrars often own domains for other registrars and the cycle sometimes goes on a few level. The best thing to do is track one by one form the whi is listing. If the registrar mentioned in who is says that the domain is actually owned by some other registrar then they will be able to give name and a contact number. I have had to at times call 4 or 5 different companies in the chain but have ultimately been able to find the right one. I think this due to reselling between registrars.