You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: Sharon Robinson here. Actually I made a earlier reservation to go for a trip with my friends, but heavy work load in office I want to change my reservation.

ASSISTANT: Sure, I am here to help you with this. There is a reservation found under your name to change, can you please share me with your dates of journey?

USER: My trip dates will be 04/07 and 04/09.

ASSISTANT: Ok, may I know your respective airports codes please?

USER: My airport codes will be AUS to DCA.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say, that there are no flights found as per your travelling details.

USER: That's ok, I will try in another alternate way. Thank you.

ASSISTANT: You are welcome always.