You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello.

USER: I am Daniel Martin.

ASSISTANT:  How can I aid you?

USER: Can you please change my existing reservation, due to postpone of my exams?

ASSISTANT: Ok, please wait I will revert you in a moment.

USER: Sure.

ASSISTANT:  Sorry to inform you that no reservation was found on your name in our data base.

USER: Ok, no issue. Thank you for your information.

ASSISTANT:  Thank you for availing us.