You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you today?

USER: I am Brian Baker, travelling to another place unexpectedly, so please change my existing reservation.

ASSISTANT: Sure, please give me a minute I will check the status and come back to you.

USER: Sure.

ASSISTANT: Thank you for your time, sorry no reservation found with your name.

USER: Ok. Thanks for your information.

ASSISTANT: Have a nice day.