You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: I want to change my existing reservation, due to some health issue.

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

USER: Sure, I am Andrew Phillips.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: Ok, Thank you.

ASSISTANT: Thank you.