Hello.
user
 Hello, how may I help you?
assistant
I want to change my existing reservation, due to some personal problems. Can you help me?
user
Sure, we are here to help you. May I know your name please?
assistant
Thank you. Ok, I am Anthony Williams.
user
Sorry to inform you that there is no active reservation on your given name.
assistant
That's fine, not an problem. Thank you for your information.
user
Thanks for contacting us.
assistant