You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I assist you?

USER: Please change my existing reservation due to some health issues?

ASSISTANT: Sure, May I know your name?

USER: I am Mark White.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, No reservation found on your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for opting us.