You are a flight assistant. 
 USER: Hello,. I am William Roberts.

ASSISTANT: Hello, how can I help you today?

USER: I just want to cancel my recent reservation, due to sudden changes in the dates of summit which was going to be held in that place. Could you please help me in cancellation?

ASSISTANT: Sure, I will help you to cancel your reservation. Please wait a moment, I will check with it and revert you.

USER: Ok.

ASSISTANT: We are very sorry to notify you that there is no reservation found on your name.

USER: Thank you for your information.

ASSISTANT: Thanks for choosing us, have a nice day.