I'm actually totally surprised by their answer. Usually AdCom people are far more accommodating.
Of course you should NOT get aggressive. That will never work. It just pisses people off. But see if you can't work with them to come up with a solution. Maybe offer them a cop of the "wrong" Transcript with a written letter signed and sealed from the school saying that it's yours. And then update them. I am sure you can find a solution! The important thing is to work with them and to try to negotiate some compromise that will work for you as well.
Best of luck, and let us know how it goes.
If you like the post, give it a KUDOS!