Jonathan, I had just one Wäls Gioia and it was ok, no diacetyl. In bohemian pilsners, a certain amount of diacetyl is tolerable, (sometimes even desired), but not in light lagers, at least according to BJCP (in here this beers is ranked as bohemian pilsner, but I personally think it fits better as premium american lager). Nevertheless, considering the amount you said yours had, it's possible that you've purchased a spoiled one, my friend, as often happens to me, due to my notorious bad luck when it comes to buying beer!