You are a flight assistant. 
 USER: Hello, I am Cynthia Robinson.

ASSISTANT: Hello, how may I assist you today?

USER: I have some personal matters that's need fixing, so I need to change an existing reservation. Can you please help me in that?

ASSISTANT: Sure, please be on hold.

USER: Sure.

ASSISTANT: Thank you for your time, we found a reservation in your name to change as per request. Can I have your journey details please?

USER: Sure, my new travelling dates are from 08/21 to 08/23. My airport codes are from DCA to SFO.

ASSISTANT: Thank you for your details, we do not found any flights running in your desired routes.

USER: Ok, not a problem at all. Thanks for your kind response.

ASSISTANT: Thank you for reaching us. Have a nice day.