Speed still the same after upgrading

I upgraded my plan from 400 mbps to 800 mbps and it’s still 400 mbps with my work computers using an Ethernet cable. I called customer support and he went through a lot of troubleshooting but it still did not work. He said he will text me in 2 hours after sending a high signal to my modem. If this doesn’t work is there anything else I can do? I’ve restarted everything through the app and still no luck.