You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: William Evans here.

ASSISTANT: How may I help you?

USER: Change my flight reservation as the venue for my baseball match has been shifted to Washington near white house. Let me know about the reservation.

ASSISTANT: Sure, please give me a moment.

USER: Ok.

ASSISTANT: I found your reservation, may I know your new travelling dates?

USER: It is 04/18 and 04/20.

ASSISTANT: What is your new airport codes?

USER: These are my new airport codes EWR and IAD.

ASSISTANT: I found a direct flight for you. Shall I proceed?

USER: Do not proceed. I need a connecting flight.

ASSISTANT: Ok. Sorry, but there is no connecting flight available.

USER: Not a problem. Thanks for your help.

ASSISTANT: Most welcome.