See if there are any changes to interline discounts coming. THAT is where Express is getting "inappropriate use" of the discount. Friends of airline employees would get their shipments made though Express at half what it would cost them had they gone over the counter. A LOT of revenue was lost there.
When I was a Courier, I'd see the same individual continuously shipping packages all over the place, even international. I knew this individual didn't know people all over the world (it was Ground "interline"), so what they were doing, was taking their friends shipments into Office, calling them "personal shipments", then getting reimbursed after the shipment was made from their friends.
What Express needs to do, is limit the number of shipments that an employee can make in a given year (tracking that would be difficult though). Use up your "discounted" shipments for the year, and you're paying full rate. Solves the problem.