You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how could I aid you?

USER: As my appointment with my doctor got postponed, can you help me to change my existing reservation?

ASSISTANT: Sure. May I know your name please?

USER: Sure, my name is Joseph Lee.

ASSISTANT: Please hold on a moment, I will check and revert to you.

USER: Sure.

ASSISTANT: Sorry to tell that there is no reservation found on your name.

USER: That's ok, thank you.

ASSISTANT: Thank you.