You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for today?

USER: I am Daniel Taylor. I am planning to change an exiting reservation, due to health issue. Can you please change my reservation?

ASSISTANT: Sure, I am here to help you with that Daniel Taylor.

USER: Thank you.

ASSISTANT: I have found your reservation with your name. Can you please provide your modified dates of journey?

USER: I would like to travel on Mar 07 and return back on Mar 09.

ASSISTANT: Can you please provide respective location codes of journey?

USER: My source code is SEA and destination code is PHX.

ASSISTANT: Do you have any other requirements about your journey?

USER: Yes, my depart time is afternoon.

ASSISTANT: I regret to say this Daniel Taylor, there are no flights as per your requirements.

USER: That's fine, thank you for your service.

ASSISTANT: You are welcome, thank you for reaching us.