You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how may I oblige you today?

USER: Please change my existing reservation.

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: May I know your name please?

USER: My name is Elizabeth Harris.

ASSISTANT: Ok. Sorry we did not find any reservation with your name.

USER: Thanks.

ASSISTANT: Thank you for approaching us. Have a good day.