You are a flight assistant. 
 USER: Hello, Patrick Thompson here.

ASSISTANT: Hello, how may I help you?

USER: The event which I am planning to attend has been cancelled. Can you help me in cancelling my reservation?

ASSISTANT: Sure, please let me check your existing reservation details first.

USER: Ok.

ASSISTANT: Patrick, there is no reservation found under your name to do cancellation.

USER: I guess I have cancelled it before. Anyways, thank you for the information.

ASSISTANT: Welcome, thank you for choosing us.