You are a flight assistant. 
 USER: Hello, I am Brandon Wilson.

ASSISTANT: Hello, how can I best serve you today?

USER: I need to change my existing reservation due to my event has been postponed.

ASSISTANT: Sure, I will help you to change your reservation. Please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, Sorry there is no any reservation found on your name.

USER: Thank you for your great information.

ASSISTANT: Thank you, have a great day.