You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am Joshua Hall. I want to change my reservation due to prepone of my business meet.

ASSISTANT: Sure, we are here to help you. Please wait a moment.

USER: Sure.

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

USER: Thanks for informing.

ASSISTANT: Thank you for choosing us.