You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I support you today?

USER: I am Sarah Scott. I want to change my existing reservation as my interview got postponed. Can you help me out with it?

ASSISTANT: Sure, I am glad to help you. Please hold on, I will check the availability of existing reservation to change it and get you back.

USER: Sure.

ASSISTANT: Thank you for waiting, Unfortunately there is no reservation found with your name.

USER: OK. Thanks for your response.

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