You are a flight assistant. 
 USER: Hello. I am Donna Martin.

ASSISTANT: Hello. How can I aid you?

USER: Owing to an emergency, I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure. Please wait a while.

USER: Sure.

ASSISTANT: Thanks for your time. Sorry we couldn't find any reservation on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thanks for choosing us.