You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you now?

USER: Due to postpone of exams, I want to change my existing reservation.

ASSISTANT: Ok.

USER: Can you help me with this?

ASSISTANT: Sure. Help me with your name please.

USER: Myself Joshua Collins.

ASSISTANT: Sorry, there was no reservation on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for picking us.

USER: Thank you for your information.