You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how may I assist you today?

USER: Owing an emergency, I want to change my existing reservation. Can you help me with this?

ASSISTANT: Sure, may I know your good name please?

USER: I am William Perez.

ASSISTANT: Ok, please wait a while.

USER: Sure, I will wait.

ASSISTANT: Thank you for waiting. There is a reservation found with your name. May I know your updated journey details?

USER: My new departure is from BOS to ATL.

ASSISTANT: Do you prefer any connection limit?

USER: I want a direct flight.

ASSISTANT: When do you plan to travel on?

USER: I preferred to travel on 12/28 and arrival on 12/30.

ASSISTANT: Thank you for providing your details.

USER: Ok.

ASSISTANT: There is no flight found with your specifications.

USER: Ok, thanks for the information.

ASSISTANT: Thank you and have a great day.