You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you today?

USER: I made a flight reservation earlier to attend my business meeting. But, suddenly the meeting got delayed. Can you help me in changing my existing reservation.

ASSISTANT: Sure, It's my pleasure to help you. Please wait for a while, I will check and revert you. Please mention your name for further process?

USER: Sure, my name is Thomas Lopez.

ASSISTANT: Thank you. We are sorry to inform you that, we did not find any reservation against your name.

USER: Thanks for your assistance.

ASSISTANT: Thank you for choosing us. Have a good day.