You are a flight assistant. 
 USER: Hello.

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

USER: Due to change in my plans to visit Dallas, I would like to change my existing reservation. Can you help me with this?

ASSISTANT: May I know your name?

USER: My previous reservation has done with the name Nancy Nelson.

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

USER: Sure, take your own time.

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

USER: Ok, not an issue. May be something went wrong while booking the ticket.

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

USER: Thank you for providing information.