You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, could you please tell us for what help you approached us?

USER: Due to some entrepreneurship meeting, I am going to change my existing reservation. Can you help me?

ASSISTANT: Sure, could I have your name please?

USER: Sarah Brown here.

ASSISTANT: Ok, please allow me a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes further.

USER: No problem, Thanks for the information.

ASSISTANT:  You are welcome, have a great day.