You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I guide you?

USER: I want to change my reservation, can you please help me?

ASSISTANT: Sure, I can help you. Please provide your name?

USER: My name is Nancy Davis.

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

USER: Thank you for the information.

ASSISTANT: Have a good day.