You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you today?

USER: I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, we are here to help you. May I know your good name please?

USER: Angela Carter.

ASSISTANT: Please wait a minute.

USER: Ok.

ASSISTANT: Sorry, there is no active reservation on your name to change.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for availing us.