You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you for the day?

USER: My appointment with doctor got postponed, so I want to change my existing reservation.

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May, I know your good name?

USER: Sure, Sarah Miller here.

ASSISTANT: Sorry, we found no reservation on your given name.

USER: Ok, no issues. Thank you for your assistance.