You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How may I help you?

USER: Please could you book a ticket from Washington DC-IAD to Phoenix, AZ-PHX.

ASSISTANT: Ok, mention your dates of travel.

USER: Depart date is 09/23 and will return by 09/25.

ASSISTANT: I need your name to proceed further.

USER: My name is Angela Roberts.

ASSISTANT: Sorry, there is no flight for you on your preferable dates.

USER: Thanks.

ASSISTANT: Thanks for choosing us, have a good day.