Hello.
user
Hello, how can I assist you?
assistant
I want to  change my existing reservation. Could you help me with that?
user
Sure, I can help you with that. May I know your good name please?
assistant
Nicole Jackson.
user
Nicole Jackson, there is no active reservation found under your name to do changes in that.
assistant
That's ok, no problem. Thank you.
user
Thank you for choosing us.
assistant