Upload speed 5 times slower than advertised

I upgraded my internet plan to 1200mbps download and 200mbps upload (my plan clearly states those speeds) and my upload speed is 40mbps max no matter what (I'm on Netgear CAX80 and getting 950mbps download and 40mbps upload according to multiple speed tests). I have IT background and I know for a fact that something is going on at the ISP's end (throttling/capping/hoping users won't notice, whatever you call it) and not on my end. I spent almost an hour speaking to a rep explaining that it's not my router and no need to send a tech to my house as the issue is not with my equipment or wiring. I found a thread with exact same issue as mine so that means I'm right. 

https://forums.xfinity.com/conversations/customer-service/not-getting-comcasts-new-200mbps-upload-speeds-support-edited/63f4698542546f76d9f3059b" target="_blank" rel="noopener noopener noreferrer">https://forums.xfinity.com/conversations/customer-service/not-getting-comcasts-new-200mbps-upload-speeds-support-edited/63f4698542546f76d9f3059b

I need Comcast to fix my upload speed to be what I pay for.