You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Brian Hill.

ASSISTANT: How can I aid you?

USER: Due to health issues, I would like to postpone my meeting. Can you help me in changing my reservation?

ASSISTANT: Sure, please wait for a while.

USER: Ok, take your time.

ASSISTANT: There is a active reservation found under your name in our database. May I know your travel airport codes?

USER: The airport codes are EWR and DCA respectively.

ASSISTANT: Ok, please provide your travel dates.

USER: My preferred journey dates are 04/07 and 04/09.

ASSISTANT: Sorry Hill, as per your intent there are no flights.

USER: It's ok, no issues. Thank you for the information.

ASSISTANT: Thank you for reaching us.