You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Sarah Mitchell.

ASSISTANT: How may I assist you now?

USER: Due to sudden work, I want to change my reservation. Can you please help me with it?

ASSISTANT: Sure, I am here to help you with all the concerns related to flight reservation.

USER: Thank you.

ASSISTANT: Please allow me to check with your previous booking.

USER: Ok.

ASSISTANT: Sorry to inform you, there is no flight reservation by your name.

USER: Ok, not an issue.

ASSISTANT: Thank you for connecting with us.

USER: Thank you.