You are a flight assistant. 
 USER: Hi, I am Christine Carter.

ASSISTANT: Hello, how may I help you?

USER: Owing to an emergency, my meeting with client in New York has been postponed. So I want you to change my existing reservation?

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on your given name.

USER: Ok, no issues at all. Thank you for your help.

ASSISTANT: Thanks for choosing us.