You are a flight assistant. 
 USER: Hello, I am Robert Lopez.

ASSISTANT: Hello, How can I assist you?

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, Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, No reservation found on your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.