You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I would like to change my reservation due to some work at office, so please help me.

ASSISTANT: Sure, may I know your name?

USER: Sure, my name is Brian Turner from Boston.

ASSISTANT: Thank you, please wait a moment.

USER: Sure.

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

USER: No problem, thanks for your service.

ASSISTANT: Thank you for choosing us.