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

ASSISTANT: Hello, How may I serve you?

USER: Due to heavy snowfall, I want to change my existing reservation, Can you help me out?

ASSISTANT: Sure, Please wait a moment I will check and let you know?

USER: Ok.

ASSISTANT: There is no reservation found with your name.

USER: Ok, thanks for the information.

ASSISTANT: Thank you for contacting us. Have a nice day.