You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you today?

USER: I need to change my existing reservation, which is done recently. Can you please help me out?

ASSISTANT: Sure, I am here to help you.

USER: Thank you for considering my request.

ASSISTANT: Can I know your name please?

USER: Sure, myself Margaret Lewis.

ASSISTANT: I regret to inform that there is no reservation found with your name in our records.

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

ASSISTANT: Thank you for contacting us, have a nice day.

USER: Thank you for your service.