You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I am Nancy Nelson. I want to book a business class flight ticket. Can you help in booking it?

ASSISTANT:  Can you please provide your journey dates for better search of flights availability with your requirement?

USER: 11/21 and 11/23 are my travelling dates.

ASSISTANT:  Please provide your airport codes that you want to travel.

USER: IAD and EWR are my airport codes.

ASSISTANT: Ok, please hold on a moment, I will check flight availability in this route.

USER: Ok.

ASSISTANT: Sorry, there is no flight service available on this route on your provided dates.

USER: No issue.

ASSISTANT: Thanks for approaching us.

USER: Thank you.

ASSISTANT: Welcome.