You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am not feeling well so, please help me to change my existing reservation.

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: May I know your name to check the previous reservation?

USER: Jason Perez here.

ASSISTANT: Please, wait for a while.

USER: Sure.

ASSISTANT: Thank you for your time, there is a reservation found on your name.

USER: Ok.

ASSISTANT: Please, share your new travelling dates.

USER: My travelling dates are from 04/24 to 04/26.

ASSISTANT: Can I have your airport codes please?

USER: Sure, my source airport code is NY - JFK and destination airport code is CA - OAK.

ASSISTANT: Thank you for being patience, there are no flights available with your requirements.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for contacting us.