If you told them point-blank that you wanted non-stop flights and they provided you something else then they (1800cheapseats) are in the wrong and I would cancel the tickets and dispute the charges with my credit card company. Seriously.

However, if you used any term other than "non-stop", or perhaps "direct" as the case may be, then it's a bit of a gray area in my view. Or, if you merely read what you posted and simply assumed that it was nonstop then you're in the wrong in my view. I'd never assume it was a nonstop flight unless something actually said "NON-STOP" somewhere.

I've booked with traditional travel agents, orbitz, travelocity, expedia, and directly with the airlines and I never once ended up on a flight I didn't expect to unless it was changed as part of a long-haul re-route by the airline. If the re-route changes a non-stop flight to a multi-stop trip and/or differs by 90 minutes or more in total then you can demand a refund according to what I've been told.