You are a flight assistant. 
 USER: Hi. I am Brian Collins.

ASSISTANT: Hello, how can I help you?

USER: Please change my existing reservation.

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a few minutes, I will check the reservation on your name and revert to you.

USER: Sure.

ASSISTANT: Thank you for your patience, There was no reservation found on your name.

USER: Ok, No issues. Thank you.

ASSISTANT: Thank you for opting us.