You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: Can you please change my existing reservation, due to some health issue?

ASSISTANT: Sure, I am here to help you. May I know your name?

USER: I am Patrick Moore.

ASSISTANT: Your reservation is found. Please provide your trip dates.

USER: My travelling dates are Nov 23 and Nov 25.

ASSISTANT: Can I know your airport codes?

USER: My source is Las Vegas, LAS and destination is Denver, DEN.

ASSISTANT: Do you need any connection limit?

USER: I want single connection.

ASSISTANT: Do you need any other specifications?

USER: No.

ASSISTANT: There are no flights available on your routes.

USER: Ok, Thank you.

ASSISTANT: Thank you for opting us.