You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Barbara Lewis.

ASSISTANT: May I know, How can I be your helping hand?

USER: I want to change my existing reservation, please help me out.

ASSISTANT: Sure, I can help you in that.

USER: Thank you.

ASSISTANT: Please wait, Let me check your reservation status.

USER: Ok, take your time.

ASSISTANT: Thanks for waiting. Sorry Barbara Lewis, there is no active reservation on your name to change it.

USER: No issues, thank you for the information.

ASSISTANT: Thanks for approaching us.