You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how may I serve you today?

USER: I am Janet Davis. I want change my existing reservation due to postpone of my meeting.

ASSISTANT: Sure, please wait a minute I will check and get back to you.

USER: OK.

ASSISTANT: Thanks for waiting. Unfortunately There is no reservation found against your name. Thanks for reaching us, have a nice day.

USER: Thanks.