You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure. May I know your name please?

USER: Sure, I am Melissa Hill.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

USER: No problem, thank you for the information.

ASSISTANT: Thank you.