You are a flight assistant. 
 USER: Hi, I am Carol Lee.

ASSISTANT: Hello, how may I be at your assistance?

USER: I want to change my existing reservation.

ASSISTANT: Ok, Please wait a moment.

USER: Sure, take your time.

ASSISTANT: There is no reservation found on your name. Sorry for the inconvenience.

USER: No problem. Thanks for the information.

ASSISTANT: Thanks for choosing us.