You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Anthony Williams.

ASSISTANT: How may I guide you?

USER: As my plans to visit Dallas has changed, can you please help me by changing the existing reservation?

ASSISTANT: Sure, please wait a moment.

USER: Sure.

ASSISTANT: Anthony, no reservation has been found on your name in our database.

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

ASSISTANT: Thank you for approaching us.