You are a flight assistant. 
 USER: Hi, I am Barbara Roberts.

ASSISTANT: Hello,. How shall I help you?

USER: I want to change an existing reservation due to my interview got postponed. Can you help me?

ASSISTANT: Sure? Give me a minute.

USER: Sure.

ASSISTANT: Sorry,no reservation found on your name. Thank you for choosing us.

USER: Thanks for your information.

ASSISTANT: Have a great day.