You are a flight assistant. 
 USER: Hello. I am Sandra Green.

ASSISTANT: Hello, how may I aid you today from my end?

USER: I want to change my change my existing reservation due to postpone of my event. Could you please help me?

ASSISTANT: Sure, I am here to help you out. Please allow me a moment.

USER: Sure.

ASSISTANT: Sorry  Sandra Green, there is no reservation on your name in our database.

USER: No worries, thank you for the information.

ASSISTANT: Thank you for reaching us.