You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: I am Kathleen Davis. I need to change an existing reservation. Can you help me?

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

USER: Ok.

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

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

ASSISTANT: You are welcome, have a nice day.