You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

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

ASSISTANT: Yes, sure. Please wait for a while.

USER: Sure.

ASSISTANT: There is no reservation found under your name.

USER: That's fine. Thank you for your service.

ASSISTANT: Most welcome.