Odd. I book everything through a corporate travel portal which is "Travel Online from Orbitz Worldwide Powered by Traversa" - so I'm not really clear whether that's Orbitz or not.

But I've never had an issue getting automatically re-booked or treated in any way other than like a direct customer.

In any case, my next call would be to Orbitz to see if they can fix it. If not, then back to Delta with the additional findings. I'd certainly try that before invoking "European legislation". I find agents don't take kindly to going the legal route.