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, I can help you with that. May I know your good name please?

USER: Nicole Jackson.

ASSISTANT: Nicole Jackson, there is no active reservation found under your name to do changes in that.

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

ASSISTANT: Thank you for choosing us.