You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

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

ASSISTANT: Sure, can I know your name please?

USER: Susan Smith here.

ASSISTANT: Ok, wait a moment please.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name.

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