To file a complaint for flight delay compensation, provide details such as appointment, flight name, date of birth, delayed flight date, airline name, flight efficiency claim details, documents attached, a brief description of the document, and previous communication. Include the flight number, date, departure and arrival schedule, flight cancellation email, and probable causes for delay. Include the amount tied to flight distance, delay duration, and relevant regulations. Supporting documents include boarding passes, e-tickets, airline messages, and bills for incidental expenses. Ensure your complaint is precise and straightforward to allow the airline to handle the dispute effectively.