the membership level permissions are extremely buggy, and especially when you want to restrict the amount of uplaods per time period. as well.

if some one knows the variable for the different users groups you could create a seperate html/php page and put in the condition

if ($variable)
{
header("Location: http://www.yoursite.com/accessnotallowed.php"
};

or that link could be just set to your home page. with a alert box as a notification
<script>alert'("Sorry you see more do not have enough permissions to view this feature")</script>

and put taht into the groups/even page on the server.