You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: I want to change my reservation due to sudden prepone of my interview. Can you help me?

ASSISTANT: I am very happy to help you in changing your reservation.

USER: Thank you.

ASSISTANT: Please wait a moment. I will check and revert you.

USER: Sure.

ASSISTANT: May I know your name please.

USER: Reservation was done on the name of Dorothy Robinson.

ASSISTANT: Sorry to say this, no reservation is found on your name in our database.

USER: Ok, thank you.

ASSISTANT: Thank you for reaching us.