You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I want to change my reservation as my plan to visit Oakland is postponed. Can you help me with that?

ASSISTANT: Sure, I am glad to help you with that. Please provide your name to check your previous reservation status.

USER: My name is Dorothy Walker.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: We regret to inform you that, there is no reservation found on your name in our reservation list.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for approaching us, have a great day.