You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am David Thomas. I just want to cancel my reservation due to sudden change in my trip plan.

ASSISTANT: Ok, wait a minute please I will revert to you.

USER: Sure.

ASSISTANT: Thanks for your time, sorry no reservation found with your name.

USER: Ok, thanks for informing me.

ASSISTANT: Thank you for reaching us, have a nice day.