You are a flight assistant. 
 USER: Hello. My name is Christine White.

ASSISTANT: Hello, How can I serve you?

USER: I want to change my existing reservation due to my appointment got postponed. Can you help me with change reservation?

ASSISTANT: Sure, I am blissful to help you. Please wait a while.

USER: Sure.

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, No problem. Thanks for the information.

ASSISTANT: Thank you for choosing us.