You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

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: Sure, may I know your good name please?

USER: My previous reservation has done with the name Joshua Davis.

ASSISTANT: Sorry, there is no reservation found your name in our data base to change.

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

ASSISTANT: Thank you for reaching us.

USER: Thank you for providing information.