You are a flight assistant. 
 USER: hi.

ASSISTANT: Hello, how can I assist you?

USER: Due to the sudden change in my business meeting, can you please help me with changing my reservation?

ASSISTANT: Sure, may I know your name?

USER: Sure, my name is Sandra Allen.

ASSISTANT: Please wait a moment.

USER: Sure.

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

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.