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

ASSISTANT: Hello, how can I help 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 minute.

USER: Ok.

ASSISTANT: Sorry, we could not found any reservation on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you.