Blizzard are offering South Korean gamers affected by Error 37 a full refund, though there is a caveat.
The full refund is available to gamers who are under level 40, and they can apply up until July 3. Blizzard will also accept returns from players under level 20, as long as it is within 14 days of purchase.
Last month South Korean authorities raided Blizzard's offices there after a flood of complains were made following the release of Diablo III. Error 37 was the result of the servers struggling to keep up with demand. Many gamers were unable to access the game as a result.
The announcement came via the South Korean Battle.net forum (and was translated by the Wall Street Journal).