You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I want to change my existing reservation due to postpone of my exams, can you help me with that?

ASSISTANT: Sure, I am here to help you. May I know your name please?

USER: Thank you. My name is Sandra Phillips.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Thank you for waiting, we found a reservation on your name. Can I know on which dates you want to ravel?

USER: My travel dates Jan 29 and Jan 31.

ASSISTANT: Ok, may I know your airport codes please?

USER: My new airport codes are SFO and CLT.

ASSISTANT: Ok, please let me know if you have any other preferences.

USER: I prefer direct flight.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Thank you for waiting, sorry no flights found with your details.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us, have a good day.