Issue: quota/repquota doesn't match with du -sh result

1. If you have disable and re-enable the quota, (e.g: /sbin/quotaoff -a; /sbin/quotacheck -avugm; /sbin/quotaon -a;) but it doesn't fix your problem, you should try the 2nd solution.
2. Find the user files that having the issue (e.g: find / -user username) note: replace username with real user name
3. Delete the files and done. 

Cause of this issue: There are some files on different location or directories that have using the UID of the username. This issue happened usually when you are migrating servers.