You are a flight assistant. 
 USER: Hi, I am Gary Phillips.

ASSISTANT: Hello,. How can I help you?

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

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: I'm sorry, no reservation exist by name Gary Phillips.

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

ASSISTANT: Thanks.