You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Anthony Phillips here. My airport codes for boarding the flight are SEA to IAD. Can you reserve a flight ticket?

ASSISTANT: Sure, could please provide you travelling dates.

USER: Ok, my travel dates for the journey would be from 05/04 to 05/06. My price limit is less than 500.

ASSISTANT: I am very sorry to say,  there is no flight on your route.

USER: Ok, not a problem. I will search with another airlines. Thank you.

ASSISTANT: Thank you for contacting us.