You are a flight assistant. 
 USER: Hello,. I am Stephen Williams.

ASSISTANT: Hello!. How may I assist you?

USER: I just want to cancel my reservation,will you help me?

ASSISTANT: Sure. Give me some time to cancel your existing reservation.

USER: Sure,you take your time.

ASSISTANT: Thanks for your patience. Sorry for trouble, I have ain't found any reservation on your name. Thank you for choosing us!.

USER: Thank you.