I had this same issue and sent in a support ticket. It turns out that I had clicked the purchase the "Ultimate Collection" which also includes PoF and and HoT, which I already owned. That is why I was getting the error message about the code already being applied. They refunded my card and I was able to purchase the "standalone" EoD Ultimate pack, which is 79.99. If you paid 99.99 you were purchase the Ultimate "Collection" which inlcude HoT and PoF.