You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you today?

USER: I am Thomas Brown. I want to change an existing reservation, due to my business meeting got postponed. Could you help me in changing a reservation?

ASSISTANT: Sure, I am happy to help you. Please wait for a while, I will check and revert you. Sorry, there is no reservation found on your given name.

USER: Not an issue. Thank you.

ASSISTANT: Thanks for choosing us.