You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: I want to change my existing reservation due to postpone of my exams. Can you please help me in that?

ASSISTANT: Sure, may I know your good name?

USER: Myself Daniel Miller.

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

USER: Sure.

ASSISTANT: Thank you for waiting, there is no active reservation found with the given name.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you.