Why is my Xfinity Stream data counting towards my data cap?

I am extremely frustrated right now. When signing up for the Xfinity Internet TV package, I was told multiple times that data streamed through the Xfinity Stream app did not county towards my data cap. Three weeks later and I have skyrocketed through my typical data usage and will end the month with roughly 300gb more usage than normal.

What is going on here? Has anyone else had this issue? How can I tell the difference between Xfinity Stream data and all other data? I have spent hours talking to technical support and continue to be given the runaround about our data usage.

Where can I got to see what data is through the app compared to what data is outside the app? The fact that there appears to be no way to fight these overages in outrageous.

(To be clear, I am using the Xfinity Stream app on my home wifi. Not anywhere else.)