Subdomain vhost quota interferes with the site quota
Maybe I'm doing something wrong, but it seems that the hard disk quota (don't know if its the same for the traffic quota) of a subdomain vhost overrides the quota of the parent domain. For example: if you have a client with 150MB disk space and assign 100MB to the parent domain and 50MB to the subdomain the client has no quota left, but his site is limited to 50MB