Taken from help.ea.com
Battlefield 4 Premium membership grants you 5 digital expansion packs for Battlefield 4 as they are released, two-weeks before public release dates, in fact, and a slew of other features.
Your Premium Membership, however, does not include Battlefield 4 itself, and you must also have purchased the full game in order to play Battlefield 4.
In other words, if you only bought Premium and not the game as well, there's nothing to download and you probably bought the wrong product.
If you want a refund you can click refund in order history in Origin or you can contact an EA Advisor by going to https://help.ea.com/contact-us
You will have to write some keywords about your problem, then fill out product, category and platform, press “Find Solutions” and then “I Still Need Help”. Then your contact options will appear. If live chat/phone does not appear, it might be closed in your area at the moment and you might consider changing it to: “United States” or something else in the language selector in the bottom of the page for a better result.
