You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: Is it possible for you to change my existing reservation?

ASSISTANT: Yes, it is possible.

USER: Ok.

ASSISTANT: May I know on whose name the ticket has been reserved formerly?

USER: My name is Ruth Johnson.

ASSISTANT: Sorry Ruth Johnson, there are no flights reserved on your given name formerly.

USER: No problem, thank you for checking it.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.