User Quota

I have some websites. Allr unning for two months or longer. On one website i have a lot of users that are over quota. I removed all files in .spam directory, but that did not help.
I've also moved most clamav files in tmp, but still no luck. Even completely deleting and recreating a user does not help. After recreation quotas are fillt again.
See also screenshots in: http://www.virtualmin.com/index.php?option=com_fireboard&Itemid=77&func=...