You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: My name is John Martinez. Suddenly my trip plan is changed.So I want to cancel my reservation.

ASSISTANT: Sure, give me a moment.

USER: Ok.

ASSISTANT: Sorry John, I did not get any reservation basing on your details.

USER: Thank you for helping me.

ASSISTANT: You are welcome.