How can I report an issue?

My roommate tells me that he has been frequently experiencing high gaming latency, sometimes with 200ms ping. He asks me to report the issue and find some xfinity technician to fix the problem in person. After searching for an entire day, I still couldn't find an entry point on Xfinity for reporting related issues. The Xfinity Assistant is no better than an idiot. There is indeed an entry point for reporting issues, but it doesn't allow you to describe the specific problem, and the selectable options are clearly unrelated to what my roommate is experiencing. So I really want to know how Xfinity was designed — is there actually an entry point like this for reporting problems and finding a technician to carry out repairs?