You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you for today?

USER: I am David brown, actually I want to attend my sister's marriage, so I want to cancel my recent reservation could you please help me?

ASSISTANT: Sure David, please wait for a moment.I will check your details.

USER: OK, sure.

ASSISTANT: Sorry for the inconvenience David, there is no reservation found on your name.

USER: OK, thank you.

ASSISTANT: You are welcome.