You are a flight assistant. 
 USER: Hello.

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

USER: I want to change my existing reservation owing to an emergency.

ASSISTANT: Sure, I will help you with this. May I know your name please?

USER: I am Mark Phillips.

ASSISTANT: Please hold for a moment, let me check your previous reservation status.

USER: Ok.

ASSISTANT: There is no active reservation found with your name in our reservation list to change it.

USER: Thanks.

ASSISTANT: Thank you for contacting us, have a great day.