You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am Michelle Green.

ASSISTANT: Ok.

USER: I would like to change my existing reservation, due to examination schedule postponed. Can you please help me?

ASSISTANT: Sure, will you please give me a moment?

USER: Ok, take your own time.

ASSISTANT: Thanks for waiting, there is no reservation found under your name.

USER: That's ok, thank you for your information.

ASSISTANT: Welcome, have a great day.