You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you at this moment?

USER: My name is William Clark. I would like to cancel my reservation, could you help me out?

ASSISTANT: Sure, I will help you. Please wait for a while. Sorry William Clark, there is no reservation existing on your name.

USER: That's ok. Thank you.

ASSISTANT: You are welcome, thank you for reaching us. Have a nice day.