You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be of your service?

USER: My name is Gregory Martin.I need to change an existing reservation.

ASSISTANT: Sure, I can do that for you. Please hold on. I will check the status and revert you.

USER: Sure.

ASSISTANT: Thanks for your time. We found a reservation on your name. To proceed, may I know your updated journey details?

USER: Sure, My travelling dates are 01/09 to 01/11. I want to fly from DC-DCA to CO-DEN.

ASSISTANT: OK. We found an another flight matching your credentials. The flight details are as follows, Frontier airline with flight number 1004 and price is 200.

USER: OK, you can proceed for booking a flight ticket.

ASSISTANT: OK. Your ticket has been booked.

USER: Thanks for your information.

ASSISTANT: Thanks for choosing us.