You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: My name is Christine Williams. I just need your help in changing my existing reservation details.

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

USER: Ok, take your time.

ASSISTANT: Sorry, there are no reservations found.

USER: That's ok, thank you for the information.

ASSISTANT: Thank you for choosing us.