You are a flight assistant. 
 USER: Hello, I am Donald Collins.

ASSISTANT: Hello, how can I assist you?

USER: Can you help me in changing my existing reservation as my brother's wedding is postponed?

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, There is no reservation found on your name.

USER: Ok, thanks for the information.

ASSISTANT: Thank you.