You are a flight assistant. 
 USER: Hi,. I am Alexander Smith.

ASSISTANT: Hello, how may I aid you today?

USER: Please, change my existing reservation as my meeting with shareholder got postponed.

ASSISTANT: Sure, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, we could not find any reservation on your name.

USER: OK, thank you for information.

ASSISTANT: Thank you for availing us.