You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I want to change my existing reservation due to postpone of my exam dates. Can you please help me with this?

ASSISTANT: Sure, may I know your name?

USER: My name is Benjamin Campbell.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, we found a reservation on your name. Can you please share your travelling dates?

USER: My new journey dates are Sept 25 to Sept 27.

ASSISTANT: Please share your airport codes.

USER: My airport codes are IAH to BOS?

ASSISTANT: Do you want connecting flight or direct flight?

USER: I need a direct flight.

ASSISTANT: Is there any specifications?

USER: I would like to prefer business class.

ASSISTANT: Sorry, there are no flights found based on your details.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for choosing us.