You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I am planning to change an existing reservation, due to health issue. Can you please change my reservation?

ASSISTANT: Sure, may I know your name?

USER: My name is Nicole Lee.

ASSISTANT: Sorry, there is no reservation on your name.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you.