You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, I am happy to help you and can I know your name please?

USER: Sure, my name is Frank King.

ASSISTANT: Please allow me a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation found for the user name in our data base.

USER: That's ok, thank you for checking.

ASSISTANT: You are most welcome and thank you for reaching us.