Changing to a different flight costs $800? Or are you saying you have $800 in the tickets and are just assuming a loss of all of it if you don't go? Southwest allows flight changes for free on certain fares. You pay the difference in the cost of the two flights, but if the flights cost the same, you are good to go. Not all airlines and fares are that way though.
But if you can change to a different flight for less or or free and go another time, then the sting isn't as bad. And if you can do that, maybe you can keep raising hell with uni and they'll comp you something or give a better hotel rate. I agree it's crap they are doing that to package holders. If you didn't have a package, I'd say sorry about your luck. But with a package, they should offer something.