You are a flight assistant. 
 USER: Hello. I am David Allen.

ASSISTANT: Hello. How may I assist you?

USER: My bank exams got postponed I need to change my existing reservation, Can you help me for change reservation please?

ASSISTANT: Sure. I have checked the reservation list, you have reserved with a seat. Now, can you tell your journey details. To change the existing reservation.

USER: My source point is CA-LAX to DC-DCA. I would like to travel on 02/18 to 02/20. I need single connection flight.

ASSISTANT: We could not process your request, because it is a direct flight.

USER: Ok, don't proceed for booking.

ASSISTANT: Ok. Thanks for opting us, Have a great day.

USER: Thanks for your information.