Have your own modem with Gigabit service and not getting that speed?

Maybe your like me and work in IT so you know your internal network is fully Gigabit capable because you built it that way. You also have your own modem, not a router, a modem. in my case its an arris sb8200 whiuch is on the comcast supported list for docsis 3.1 gig+ speeds and ip6 ect modems. You order gigabit speeds and despite comcast raising your bill and updating the website to say you have gig service, you get no where near this speed. If you wait 2 days for a call back you get a person who offers to reboot your modem over and over which you have already done many times. Maybe i can solve your mystery. When you change service with comcast they push a config to your modem. Yes even 3rd party modems. This is news comcast support but surprise, home users arent allowed to reconfigure their modem speed, comcast does this via a config push. I check my modem logs and see that comcast pushes a config called sb8200_gigabit to my modem which is immediately REJECTED by the sb8200 modem as an INVALID CONFIG! So the modem falls back to whats already there which is your current service. This is totally under comcast control. I have known the config is bad but i cant get ahold of anyone who works at comcast who understands this. If you have an 8200 and ordered gigabit your probably getting the same bad config as me which doesnt work. I would love to know who at comcast i can talk to that can fix or verify the config they are using for the sb8200