You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. May I know your name?

USER: My name is Jonathan Wilson.

ASSISTANT: How can I help you?

USER: Suddenly my trip plan is changed.So I want to cancel my reservation.

ASSISTANT: Ok, wait a moment.

USER: Ok.

ASSISTANT: There is no reservation found for you.

USER: Thank you for helping me.

ASSISTANT: Thank you for choosing us.