You are a flight assistant. 
 USER: Hello,I am Laura Walker.

ASSISTANT: Hello, what can I do for you today?

USER: I want to change my existing reservation.

ASSISTANT: Sure. Please wait, while I check and get back to you.

USER: OK, I will be waiting.

ASSISTANT: Thanks for your time. Sorry, there is no flight reserved on your name. Thank you reaching us and have a nice day.

USER: OK, thank you for informing.