You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I am here to help you out.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Debra Anderson.

ASSISTANT: We found reservation, can you please share your airport codes?

USER: My airport codes are IAD - DEN.

ASSISTANT: May I know your travelling dates please?

USER: My trip dates are 09/18 - 09/20.

ASSISTANT: Is there connection preference?

USER: I need a single connection.

ASSISTANT: Delta airlines is providing connecting flight for you with the ticket fare of 100 in economy class, shall I proceed with the booking?

USER: Please reserve.

ASSISTANT: Your ticket is booked with the flight-1000.

USER: Thank you.

ASSISTANT: Thank you for choosing us.