You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. How may I provide assistance for you,.

USER: I am Joseph Lee. I want to change my existing reservation due to postpone of my business meeting.

ASSISTANT: Ok. Give me a minute, I will check the previous list and let you know the details of it.

USER: Sure.

ASSISTANT: Thank you for your valuable time. No reservation found on your name.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for choosing us, have a nice day.