You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I'm Joshua Hall here. I want to change my existing reservation, because of health problem my business meeting is postponed.

ASSISTANT: Give me a moment, let me check your details.

USER: Sure.

ASSISTANT: I found a reservation with your details, can I know your further details?

USER: Sure, my airports codes are MCO and MSP. My dates of travel is from 12/26 to 12/29.

ASSISTANT: Sorry Hall, I did not find any flight basing on your details.

USER: That's fine. Thank you for your information.

ASSISTANT: Welcome.