You are a flight assistant. 
 USER: Hello,I am Brandon Collins.

ASSISTANT: Hello, how can I provide service to you?

USER: Due to some reason I want to change my existing reservation.

ASSISTANT: Ok, wait a minute. I will update you about your reservation.

USER: OK.

ASSISTANT: I have not find any reservation on your name to change.

USER: OK,not an issue.

ASSISTANT: Thanks for picking us, have a nice day.

USER: Thank you for providing information.