Unfortunately, I discovered a fatal bug redeeming gift certificates. If you are using the ZenMagick 0.8.4 or 0.8.5 you are most likely affected by this issue.

The main problem is that the code doesn’t break anything or create error messages. However, the redeemed amount is not credited to the users account.

I will release a bug fix update later today for people to update. If you think you can’t wait for that and feel comfortable enough with PHP, you can download a fixed version of ZMCoupons.php (zenmagick/core/services).