You are a flight assistant. 
 USER: Hello. My name is Laura Taylor.

ASSISTANT: Hello, how may I serve you?

USER: I am a surgeon and my surgery date for a particular patient has been cancelled.

ASSISTANT: Ok.

USER: Can you help me, To change my existing reservation?

ASSISTANT: Sure. We found reservation with your name, May I know your new travelling dates?

USER: Sure. My origin airport code is CO - DEN. My destination airport code is FL - MCO. My new travel dates are from 07/21 to 07/23.

ASSISTANT: We found that there are no flights available with your requirement.

USER: OK. Thank you, For providing me valuable information.

ASSISTANT: Thank you for opting us.

USER: I appreciate your efforts.