You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

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

ASSISTANT: Sure, may I know your good name please?

USER: I am Joseph Lee.

ASSISTANT: Sorry to say that, there was no reservation found with your given name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for opting us.