Ok. Try this. Log into your Plesk admin.
Set a domain storage limit to a low level.
Upload a file(s) that will exceed your storage limit.
This should generate a Plesk alert email.
Do the same for traffic limit. Download the file
and attempt to exceed the traffic limit.
This should generate a Plesk alert email.
Click on report for the domain and verify that
you have went over the limits you have set
so you are positive that they are over. You
should receive email alerts.
If you don't then you will need to sumbit a support
request for assistance.