Hi Nancy,
To the extent that IT has permission to order "IT Services" (and the customer doesn't), you actually can accomplish this. Turn off the setting in Administration > Settings for "Display Empty Categories", and combine this with the use of ordering permissions to control the categories that appear to the logged in user. When this setting is turned off, a category is considered to be empty if there are no services in that category that a user may order. In addition, if IT is i