You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation, because of postpone of my exam.

ASSISTANT: May I know your name for further proceedings?

USER: Myself Katherine Miller here.

ASSISTANT: Sorry Miller, no reservation found by your name.

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

ASSISTANT: Thank you for contacting us.