You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I render you today?

USER: Owing to an emergency, I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, may I know your name?

USER: Myself Donald Perez.

ASSISTANT: We found a reservation on your name, can you please share your airport codes?

USER: My airport codes are SFO, OAK.

ASSISTANT: May I know your travel dates?

USER: I want to fly on Feb 26 and return on Feb 28.

ASSISTANT: Do you have any specifications?

USER: I would like to prefer business class.

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: Sorry, there were no flights found with your specifications.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for opting us.