sporadically slow speeds on gig plan

I'd prefer to create a support ticket, but it looks like that's not possible through you website.  I pay for gig speeds, and most of the time or connection is fine.  Periodically, especially between the hours of 5-8pm, our speeds drop to < 10Mbps, making it mostly unusable at the times we want to use it the most.  I have a modem and router that easily support those speeds, and checking on hardwired and wireless devices shows the same results, despite QoS settings.  I've tried resetting/restarting everything in-home with no success, and double-checked all my device configurations which look fine, which leads me to believe it's an Xfinity issue.  How can I get a real human to analyze the traffic and help with this?  P.S. your chatbot is useless and almost definitely contributes to your churn numbers.