You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you?

USER: William Davis here. Can you cancel my flight ticket reservation? As I want to postpone my business trip in Chicago.

ASSISTANT: Sure, please give me a moment.

USER: Ok.

ASSISTANT:  I am sorry there is no reservation found for the user name which you have provided.

USER: Not a problem.

ASSISTANT: Thank you for reaching us, have a nice day.

USER: Thanks for checking.