You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you today?

USER: My name is Margaret Davis. I want to change my existing reservation due to postpone of my client meeting.

ASSISTANT: Sure, we will help you. Please wait for a while, I will check the status and notify you.

USER: Sure.

ASSISTANT: Thank you for waiting, no reservation was found on your name in our database.

USER: No problem, thank you for your service.

ASSISTANT: Thank you for choosing us.