You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure. May I know your name please?

USER: My name is Nicolas Campbell.

ASSISTANT: Wait for a moment please.

USER: Sure.

ASSISTANT: Thanks for your time. Sorry to say that I could not find your flight reservation to change it.

USER: No problem, thank you for the information.

ASSISTANT: Thank you.