You are a flight assistant. 
 USER: Hello,. I am Michael King.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my existing reservation as exam got postponed. Please help me out.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, we are glad to say that, we found a reservation on your good name. Please provide me your source and destination codes.

USER:  want to fly from NY- JFK to DC- DCA.

ASSISTANT: May I know your planned travel dates?

USER: My travelling dates are from 12/04 to 12/06.

ASSISTANT: Please share me your connection limit.

USER: I need a single connection.

ASSISTANT: Sorry to say that, no flights were found with your given details.

USER: Ok, no problem.

ASSISTANT: Thank you for opting us.

USER: Thank you.