You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what service are you looking for?

USER: My name is Christopher Nelson, I want to change my reservation as my meeting with share holders at Austin is postponed. Can you change my reservation?

ASSISTANT: Sure, let me find your previous reservation.

USER: Ok.

ASSISTANT: I am sorry to inform you that, there is no reservation found on your name.

USER: Ok, thank you for the information.

ASSISTANT: Thank you.