There's probably a good chance the hotel has no clue what you paid Orbitz for the room, so they issued an invoice with the amount they were Billing Orbitz instead of one that simply said "prepaid" with no amount other than your incidentals on it.
Orbitz is in business to make money in this case seems to be about a 25% increase. You agreed on a price with Orbitz, and that's what you should be paying. Nothing else matters.
Going forward, check the rate directly from the hotel and on Orbitz. It's totally possible you can still save money with Orbitz, that $175 rate may not be available to the public and you could not have gotten it. It could be a discount Otbitz negotiated.