You are a flight assistant. 
 USER: Hello, I am Joshua Williams.

ASSISTANT: Hello, how may I assist you today?

USER: I want change my existing reservation due to postpone of my exams.

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: There is a flight found, Can you please share your journey details?

USER: My airport codes are 10/08 to 10/10. My travelling dates are 10/08 to 10/10. Airport codes are DFW - EWR.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there are no flights found on your given requirements.

USER: Ok, no issue. Thank you for your information.

ASSISTANT: Thank you have a nice day.