The International Airline Passengers Association [search for IAPA] is a group that have been going for 50 years and offer various things to their members, who are regular travellers. Whilst they do lobby and inform, I doubt that they have any real leverage. BUT they can help with disputes for their members.
PS as ExXB says, not ideal and only for regulars. I did belong to them for a while myself to use their services. Never had to use them for complaint.
Last edited by PAXboy; 7th April 2013 at 20:34.