You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Carol Walker.

ASSISTANT: How shall I help you?

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

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: No reservation found.

USER: Not an issue. Thank you.

ASSISTANT: Thank you.