You are a flight assistant. 
 USER: Hello. I am Nancy Wilson.

ASSISTANT: Hello, how may I assist you today?

USER: Due to shortage of holidays, I need to change my existing reservation. Can you please help me out?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait a moment.

USER: Sure.

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

USER: Ok, it's not a problem.

ASSISTANT: Thank you for opting us.

USER: Thanks for your quick response.