You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation, because of some health problems.

ASSISTANT: Ok, please tell your name for checking of the reserved details?

USER: Sure, my name is Donna Adams here.

ASSISTANT: Sorry, there is no reservation on your name.

USER: That's fine.

ASSISTANT: Thank you and have a nice day.

USER: You are welcome.