You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: My name is Jason Collins. I would like to change my existing reservation, can you help me with that?

ASSISTANT: Sure, I am gleeful to help you to change your reservation. Please hold on for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, no reservation found on your name to change your reservation.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for opting us, have a great day.