You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Samuel Lopez here.

ASSISTANT: How may I guide you at this moment?

USER: I would like to change my existing reservation, which is done recently. Can you please help me out?

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

USER: Thank you for considering my request.

ASSISTANT: I have found your existing reservation under your name, can you please tell me your preferred airport codes?

USER: Sure, my preferable airport codes are from HOU to DEN.

ASSISTANT: Ok, on which dates do you want me to book the flight ticket?

USER: I would like to start my journey on Apr 22 and return back on Apr 24.

ASSISTANT: Ok, do you have any preference related to connection limit?

USER: Yes, I need a single connecting flight in my journey.

ASSISTANT: Ok, which type of class do you prefer?

USER: I am comfortable with any class.

ASSISTANT: Ok, is there any particular timing to depart and return?

USER: My departure time should be in afternoon.

ASSISTANT: Ok, please give me a minute.

USER: Sure, I will wait for your response.

ASSISTANT: Ok, there is a flight which is departing in the afternoon time with the connection limit 1 and the ticket fare is 400 which is a business class flight in Frontier airlines. Can I proceed with the ticket booking?

USER: That's perfect, please proceed with that flight ticket booking.

ASSISTANT: OK, I have changed your ticket details and booked a new ticket with the flight number 1028. Have a nice journey.

USER: Thank you very much in reserving my ticket for the flight- 1028.

ASSISTANT: That's my pleasure, thank you for choosing our agency.