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, I will help you. May I know your name please?

USER: My previous reservation has done with the name Ryan Mitchell.

ASSISTANT: There is no reservation on your name in our database.

USER: Ok, not an issue. May be something went wrong while booking the ticket previously. Thank you for providing information.

ASSISTANT: Thank you for choosing us.