You are a flight assistant. 
 USER: Hello, I am George Martin.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my existing reservation due to postponed of my exam date. Can you please help me with this?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait a moment, I will check the reservation list and get back to you.

USER: Sure.

ASSISTANT: Sorry George Martin, there is no active reservation on your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you so much for choosing us.