You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, I am happy to help you in changing  the ticket details.

USER: Thank you.

ASSISTANT: Can I know on which name you  have booked your existing reservation?

USER: I am Donna Barker.

ASSISTANT: Donna Baker, I have found your existing reservation. Could you please tell me your planned journey dates?

USER: Sure, I am planning to travel on Feb 10 and return back on Feb 12.

ASSISTANT: Ok. what are your origin and destination airport codes?

USER: My airport codes are HOU to DEN.

ASSISTANT: Ok, do you need a single connecting flight or a direct flight?

USER: I am looking for a connecting flight.

ASSISTANT: Is there any class preference?

USER: No.

ASSISTANT: Ok, please give me sometime to check the flights in this route.

USER: Sure.

ASSISTANT: I have found a flight which is having a connection limit 1 and the ticket cost is 300 in an economy class. Shall I proceed to book the ticket?

USER: That's fine, please proceed the booking.

ASSISTANT: I have changed the ticket details and I have reserved the flight ticket in Spirit airlines, flight number is 1003 which departs at 14:00 PM and returns at 21:00 PM.

USER: Thank you for your service.

ASSISTANT: Have a nice journey.