You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: Charles Hernandez  here, due to sudden changes my exams has been postponed.

ASSISTANT: Sure, I will help you.

USER: Can you please help me with changing my reservation.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, we found a new reservation on your given name. Can you please help me with your new journey details?

USER: OK. My travel dates are 08/23 and 08/25. Airport codes are SFO-OAK.

ASSISTANT: Sorry, there is no flights found on your given details.

USER: Ok, no issues. Thanks for the help.