@MIFUNE65, It looks like this is working as intended as you did not buy the standalone game of Battlefield 3 for PC, but only the Premium 'expansion', which is a DLC for the game that gives you access to certain maps, weapons, etc.
If you buy the standalone game now, via
https://www.ea.com/games/battlefield/battlefield-3 or directly via the EA app, you will have access to the game including the Premium items.
Also, if you look at
https://www.ea.com/games/battlefield/battlefield-3#add-ons, you see that Premium, on the right has side, is marked as an add-on (DLC).
Hope this helps.