You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Actually, my friend book a flight ticket in economy class instead of business class. Can you please help me in changing of my existing reservation?

ASSISTANT: Sure, may I know your good name please?

USER: Myself Catherine Wilson.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: You are most welcome.