You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I am Susan Smith. I want to change my existing reservation due to postpone of my client meeting.

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation was found with your good name.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for opting us.