You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Please change my recent reservation which previously booked on Robert Smith name.

ASSISTANT: Sure, I will help you. Please allow me a minute.

USER: Ok.

ASSISTANT: Thank you. Robert Smith, I am really sorry to inform you that there is no booking found on your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us. Have a great time.