You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I provide assistance to you?

USER: Christine Hall here, due to sudden changes my meeting got postponed. Can you please change my existing reservation?

ASSISTANT: Sure, We are happy to help you. Please wait a moment.

USER: Ok.

ASSISTANT: Thank you for waiting. I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for opting us, Have a cheerful day.