You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you?

USER: I am planning to change an existing reservation, due to health issue.Can you please help me out?

ASSISTANT: Sure, please share your name first.

USER: My name is Dorothy Hill.

ASSISTANT: We have found reservation on your name, please share your airport codes.

USER: My airport codes are DTW to LAS.

ASSISTANT: May I know your travel dates please?

USER: I am planning to travel on Aug 12 and return back on Aug 14.

ASSISTANT: Which class do you prefer to travel?

USER: I am ok with any class.

ASSISTANT: May I know your connection limit?

USER: No, I am looking for a normal cost flight.

ASSISTANT: Sure, do you have any other preference?

USER: No.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that we don't have any normal-cost airline flight available in your journey route.

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

ASSISTANT: Thank you.