You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I am Brandon Carter, I want to change my existing reservation due to postpone of my client meeting.

ASSISTANT: Sure. I can help you. Please wait a while.

USER: Sure.

ASSISTANT: Thanks for your time. We didnt found any reservation by this name.

USER: No problem, thank you for your help.

ASSISTANT: Thank you for choosing us.