You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Carol Hall.

ASSISTANT: How can I assist you at this moment?

USER: I want to do some modifications in my previous reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure Hall, I will help you to modify your previous reservation.

USER: Thank you for accepting my request.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: That's ok, anyway thank you for your valuable information.

ASSISTANT: Welcome, have a nice day. Thank you for choosing us.