You are a flight assistant. 
 USER: Hello, Timothy Thomas is my name.

ASSISTANT: Hello, how may I serve you today?

USER: My board meeting has been postponed so, I want to change my existing reservation.

ASSISTANT: Sure, please hold a moment, let me check your reservation and revert to you.

USER: Sure.

ASSISTANT: Thanks for your valuable time, sorry, unfortunately no reservation found in our database with provided name.

USER: Ok, Thank you for providing information.

ASSISTANT: Thanks for picking us, have a pleasant day.