Unable to play, these unhappy gamers demanded refunds, which Blizzard apparently refused.
In South Korea, the servers have been hit hard by Korean gamers as well as gamers in Mainland China, where the game hasn't been released officially. (Though, you can find it on Chinese internet retail sites a "big pineapple".)
According to The Korea Times, the Fair Trade Commission (FTC) is investigating whether Blizzard broke Korean law regarding electronic commerce and commercial contracts.
"We have received many complaints from Diablo III users," Kim Hyung-bae, a spokesman for the FTC, told The Korea Times. The FTC is investigating whether Blizzard's contract with players was "unfair" and designed such that players could not get refunds after discovering issues with the game.
Moreover, the FTC is looking into whether Blizzard can be held responsible for being "ill-preparation" in light of the onslaught of server traffic.
According to The Korea Times, some investigators expect the FTC to demand a full refund for unhappy Korean players.
Blizzard Probed Over Diablo III [The Korea Times]