You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you at present?

USER: Can you please help me to change my reservation due to postponed of my exam?

ASSISTANT: Sure, I am here to help you to change it.

USER: Thank you for accepting my request.

ASSISTANT: May I know your name please?

USER: Sure, my name is Joseph Lewis.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found on your name in our database to change it.

USER: No issues, thank you.

ASSISTANT: Thank you for availing our service.