Data Usage by Device

No, xfinity, for reasons we can all guess, does not provide any way to break out your monthly internet usage by specific device connected to your network.  I find this extremely frustrating because like a lot of others posting on this forum, I am suddenly for the last several months extremely close to exceeding my monthly data cap and I can't figure out why.  I've done the math on how many hours we stream 4K, use the internet, etc and I am not coming anywhere near the data cap so something is really off and all I want to do is figure out if it's a defective device or maybe even an error on xfinity side.  Why they provide no method of checking this which could easily be done at the modem level via a software adjustment that would that would show by device how much data is being used or even at the xfinity app level rather than a nonspecific rolling 24 hours that is basically useless.  

I am in process of writing a formal complaint since the people on their customer service line and advanced tech support refuse to help.  If I can't get this data, which they definitely have, then I am going to be reaching out to an attorney for the possibililty of a class action law suit.  

It is apparent to me that the reason xfinity refuses to provide their customers with a way of tracking monthly data usage by device is because they are more interested in selling clients more expensive unlimited data plans.  Every interaction I had with customer service resulted in this sales pitch.  

[Edited: "Solicitation"] that xfinity provides a way that we can track data usage by device in our households.  This isn't rocket science, there is no logical reason they are not allowing us to have this information other than to sell unlimited data plans.  This is unacceptable to me and I'm sure many of you as well.