You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you now?

USER: Katherine Thompson here. I need to change my existing reservation. Can you please help me out?

ASSISTANT: Sure, I will help you. Please wait for a moment.

USER: OK.

ASSISTANT: Thanks for waiting, sorry to inform you there is no any reservation found on your name.

USER: No issue. Thank you for the information.

ASSISTANT: Thank you have a nice day.