Blizzard has said the restrictions imposed on players that purchase Diablo 3 digitally are necessary "for security reasons and to help ensure the integrity of the game and auction house service."
As detailed yesterday unverified ditigal copies of Diablo 3 are now unable to access public games, the auction house, can't trade or drop items for other players to receive, chat in any public or game channels, attach a custom message to friend requests or access the Global Play features.
Blizzard explained: "Players who purchase the digital version of Diablo III may have to wait until payment verification is complete before they can access certain game features.
"While most payments are approved and restrictions are lifted within a day, in some cases it can take up to 72 hours to complete this process.
"Similar to World of Warcraft, these restrictions were put in place to deter credit card fraud, which in turn helps reduce gold spam and other harmful activities that can have a negative impact on the game experience for everyone."
The studio has described the cap at level 13 and inability to progress beyond Act 1 as an "unintended consequence" of the security measures which will be rectified. It also reiterated that the restrictions are temporary.
"However, as an unintended consequence of these security measures, players who purchase the game digitally after patch 1.0.3 are temporarily being capped at level 13 and not able to proceed beyond Act I. We are working to correct this as soon as possible and will provide another update when we have more details to share"
"Again, we want to be perfectly clear that these are temporary restrictions (often lifted within a day and at most 72 hours) associated with digital purchases for the protection of players. We appreciate player feedback and will continue to evaluate the best methods for ensuring a positive game experience for everyone."
Earlier this week a post on the South Korean Battle.net forum Blizzard offered Diablo 3 players that have been affected by Error 37 a full refund.