Mesaba's discount (75%) applies to Priority Overnight, Standard Overnight, Economy Two-Day, and International Priority. Of all the corporate discounts listed, this is the only one I ever use besides the special rates on hotels. I had a similar bad experience with a clerk at Kinko's. So now I just bring a printout of the page on MyMesaba that describes the discount program with me rather than trying to argue with them. If they will honor the discount on Economy Two-Day as they should, it's usually about the same or a few bucks cheaper than just going with ground (~4 day service). You basically pay the same as ground but get it 2 days faster.