You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: Can you please change my reservation?

ASSISTANT: I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name?

USER: I am Helen Roberts.

ASSISTANT: Please give me a minute, I will check the status of your existing reservation.

USER: Sure, I will wait for your reply.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: That's ok, thank you for checking.

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