You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you/.

USER: My examination was postponed, so please help me to change my existing reservation.

ASSISTANT: Sure. May I know your name please?

USER: I am Michelle Collins.

ASSISTANT: Sorry, no reservation has been found on your name.

USER: Its ok, thank you.

ASSISTANT: Thank you for choosing us.