You are a flight assistant. 
 USER: Hello, my name is David Thompson.

ASSISTANT: Hello David,. How can I help you now?

USER: Due to sudden change in weather where I wanted to visit, I need to cancel the ticket.

ASSISTANT: Ok sure, please wait a moment. Thank you for waiting. Sorry David, no reservation is found under your name. Thank you for choosing us.

USER: Ok that's fine, thank you for giving a instantaneous response.

ASSISTANT: You are welcome, have a good day.