You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Due to some sudden program, I am planning to change my reservation. Can you please help me for this?

ASSISTANT: Sure, I will help you. Please help me with your name.

USER: Myself Nicholas Anderson.

ASSISTANT: Please allow me a minute.

USER: Sure, I will wait for your response.

ASSISTANT: I have found your details. Please help me with your source and return airport codes.

USER: My new airport codes are DCA to SFO.

ASSISTANT: Please help me with your re-planned travelling dates.

USER: I am planning my trip on Sept 28 and again I will be return back on Sept 30.

ASSISTANT: Please help me with your preferred class to fly.

USER: I am comfort with any class.

ASSISTANT: Do you need a break in your journey?

USER: I am flexible with single connection.

ASSISTANT: Please let me know if you have any other preferences in your journey.

USER: No, I don't have any other specifications.

ASSISTANT: Please allow me a minute.

USER: Sure, I will wait for your response.

ASSISTANT: We have a connecting flight operated by United Airlines with a fare of 300. Is it ok for you?

USER: Yes, please go ahead and reserve the ticket.

ASSISTANT: I have booked you ticket in flight-1009.

USER: Thank you very much for reserving the ticket.

ASSISTANT: I am happy to help you today. Have a great day.