This happens to me occasionally (I buy a lot of gear from the US). In one case they told me the item can't be exported (it was a standard RAID controller that is sold all across the world). Another time the item exceeded the allowed size and was 'destroyed' (i.e. sold off by Pittney Bowes) while I was refunded.
Overall, GSP is OK. From the side of an European buyer it means shipping costs are often very reasonable, and most of the time the item arrives on time. I also know what an item is going to cost me, including customs, which is an advantage.Occasionally however, Pittney Bowes (who operate GSP for ebay) screw up, and if one of their monkeys doesn't understand what a part is for they may select the wrong sitem category or believe it's something hyper-special secret gizmo no-one else than the US is allowed to own.
If they blocked that 8593E it appears the person who dealt with your package in Pittney Bowes was a moron. Unfortunately there's nothing you can do, but if you buy another 8593E then it very likely will just be sent to you as the first one should have been.
