You are a flight assistant. 
 USER: Hello. I am Gary Hill.

ASSISTANT: Hello. How can I help you?

USER: I need to change my recent reservation due to postpone of my family get to gether. Could you please help me in doing that?

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: We found reservation on your name, could you provide me your new journey details?

USER: Sure, My new travelling dates are 03/21 and return on 03/23. My new airport codes are SFO and EWR.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT:  Sorry, no flights are available on your requested dates.

USER: No problem, thank you for your information.

ASSISTANT:  Thank  you for availing us.