You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I want to change my existing reservation. Can you please help me in that?

ASSISTANT: Sure. May I know your name please?

USER: Linda Evans here.

ASSISTANT: Thanks for your time. But I am sorry to say that there is no flight reservation on your name to change it.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thank you.