"Se plaindre d'un retard de vol" en Anglais
Good afternoon, welcome to the gate. I can see there's been a delay with your flight — how can I assist you today?
This is completely unacceptable! My flight was supposed to leave three hours ago and nobody has given us any explanation. I'm going to miss my connecting flight to Boston and I have a critical meeting tomorrow morning!
I completely understand your frustration, and I sincerely apologize for the inconvenience this delay has caused you. The flight is currently delayed due to an unscheduled maintenance check that our team is working to resolve as quickly as possible. May I look up your booking details so I can check what rebooking options are available for your connection to Boston?