Regulation (EC) No 261/2004 of the European Parliament and of the Council of 11 February 2004 establishes common rules on compensation and assistance to passengers in the event of denied boarding and of cancellation or long delay of flights, and repeals Regulation (EEC) No 295/91, establishing rules on passenger protection at the above stated event in case of both scheduled and charter flights.
Has your flight been cancelled or delayed? Have you been denied boarding?
If you are not satisfied with the reply, you can submit your complaint to the national enforcement body dealing with passenger rights. If possible, make your complaints in the countries where the incident took place.
Further information on air passenger rights available in the links and leaflets below.