You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Nicholas Robinson here, I want to reserve my ticket from IAD to SEA, can you please help me to book a ticket?

ASSISTANT: Sure, can you please tell me on what dates you need booking?

USER: Ok, my dates of journey is from 12/26 to 12/28. Please make sure that the price limit is 500.

ASSISTANT: Sorry, there is no plane as per your requested travelling dates.

USER: That's fine. Thank you for your service.

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