Write a paper (!) letter to the ceo. https://corporate.comcast.com/news-information/leadership-overview/brian-l-roberts. Include screenshots and a request for someone in his office to assign a Level 2 or Level 3 to the issue.
That has actually worked for me to get a phone call from a Level 3. Of course, the guy was super-defensive about Comcast.
That has actually worked for me to get a phone call from a Level 3. Of course, the guy was super-defensive about Comcast.