You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I am here to help you out. May I know you name please to proceed further?

USER: Sure, I am Christine King.

ASSISTANT: Christine King, we regret to inform you that there is no reservation found on your name in our records.

USER: Ok, Thank you.

ASSISTANT: Thank you for approaching us.