You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: I would like to change an existing reservation, can you please help me?

ASSISTANT: Sure, may I know your name?

USER: Sure, I am Janet Roberts here.

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

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you.