You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: Actually my Final Examination is postponed, so that I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, please hold on for a moment, let me check. Can I know your name?

USER: Yes, I am Helen Rodriguez here.

ASSISTANT: I am sorry, there are no reservations with your name in our database.

USER: Ok, not a problem.

ASSISTANT: Thank you, have a good day.

USER: Thank you for your valuable time.