Problem with updation of 'quota'

Hi,

We have recently implemented 'quota' concept for the unix users.

softlimit - 230MB
hardlimit - 250MB

We have applied the quota when few of users are more than the hardlimit,issue is that even though the users cleared the space, still its 'quota' was not updating properly.
For some cases even the users with less than 200MB physically, still its showing more than that.

Let me give a sample example if i'm not clear wat i said

Quotas for user xxxx:
/home/work/worklvextd: blocks in use: 536448, limits (soft = 230400, hard = 281600)
inodes in use: 9558, limits (soft = 0, hard = 0)

Actual size used by user xxxx:
du -sm /home/work/worklvextd/xxxx
138.39 /home/work/worklvextd/xxxx

Some times when i do 'quotacheck <filesystem>', updation done but not every time :confused:

Please help in this regard, thanks in advance.