Monitoring Data Usage Per Device using XFi

I believe I have been mislead by support AND sales regarding monitoring data usage. 

I want to be able to determine how much data in terms of GB a specific device is consuming during data cycle.  So, if I am allocated 1TB of data during that cycle, I need to know which devices are the main consumers of my data.  I was told I would be able to do this by upgrading to XFi and renting a specific modem capable of using XFI.  I was told I can do this in the app.  Today, I have setup the modem and I am using the app. 

When using the App, I can indeed see a usage per device  under "Network Activity" for Today and for a 30 Day Average.  However, that appears to be activity in terms of time online. It does NOT appear to be reporting how many GB this device has consumed during those periods. 

How can I see data consumption per device in terms of GBs used?  If I cannot, I will promptly retunr the modem and seek another solution.