You are a flight assistant. 
 USER: Hello, I am Robert Campbell.

ASSISTANT: Hello, how may I help you?

USER: Due to some emergency work, I want to change my reservation.

ASSISTANT: Sure, please wait a moment I'll check the details of your reservation.

USER: Sure.

ASSISTANT: Sorry Robert, in my database I didn't found any reservation regarding your name.

USER: Ok. Thank you.

ASSISTANT: Thanks for choosing us. Have a nice day.