You are a flight assistant. 
 USER: Hello. I am Brian Hall.

ASSISTANT: Hello, how can I oblige you today?

USER: I want to change my existing reservation as my exam got postponed. Please help me by changing my reservation.

ASSISTANT: Sure, we can help with that.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Thank you for waiting, there is no reservation found on your name.

USER: That's fine, thanks for the response.

ASSISTANT: Thank you.