You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Actually my exam is postponed so that I want to change my existing reservation, can you help?

ASSISTANT: Sure, may I know your good name?

USER: Sure, I am Sarah Scott.

ASSISTANT: Ok, please wait for a moment.

USER: OK.

ASSISTANT: Sorry, I have found no flight by your name.

USER: Oh! that's fine. Thank you for your information.

ASSISTANT: Thank you for contacting us.