Latency issues since upgrade never had before thinking about switching providers

Had xfinity for 5 years and recently upgraded my device, got a new modem followed all the steps, called and talked to three different people who had fixed it but after 1 day I’m having to call back for more latency issues and random disconnections. Frustrated to the point of just do connecting services. It’s almost impossible to get ahold of a real person, and when I finally do, my service does the same thing again after 24 hrs. Never had this problem until upgraded my service