You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Due to sudden change in my trip dates I need to change my existing reservation.

ASSISTANT: Ok. I am here to help you.

USER: Thank you.

ASSISTANT: May I know your name to check reservation?

USER: I am Nicholas Robinson.

ASSISTANT: Please, wait for a moment.

USER: Sure.

ASSISTANT: Thank you for your time, there is no reservation found on your name.

USER: No problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.