You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Could you please change my existing reservation due to postpone of my exams?

ASSISTANT: Sure, I am willing to help you for this. May I know your name please?

USER: My name is Michael Lee.

ASSISTANT: Just a moment, let me check your reservation status in our database.

USER: Sure.

ASSISTANT: Sorry to inform you, no reservation is found under your name to change.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you very much for approaching our agency.