You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I would like to book a ticket from LGA to IAD, can you please help me out?

ASSISTANT: Sure, I am glad to help you with that. Can you please provide your preferable dates of travelling?

USER: I am travelling on these dates Sept 18th and 20th.

ASSISTANT: Can I know your name to book the flight ticket?

USER: Samantha Lopez here.

ASSISTANT: Are you ok with connecting flight?

USER: I need single connected flight.

ASSISTANT: Do you have any other specifications?

USER: I prefer business class.

ASSISTANT: Please be on hold to check the flights.

USER: Sure.

ASSISTANT: We regret to inform you that, there are no business class flights are available for your journey with your requested dates of travelling.

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for approaching us, have a great day.