There are rules for removing the BS from Comacast's plate of customer service.
1) Always write down who you talked to and why you called and the date/time. This should be the first thing you ask, it's funny how they really listen after doing this
2) Never use and outside source for testing your speed. Use their tool ( http://speedtest.comcast.net/) and beat them over the head with the bad performance. Their first rule is to make sure they have full control of your test points, go outside of their network and they will wash their hands of it.
3) Be nice but firm, if you smell any BULL$H!* call them on it but be nice but firm.
4) If you feel like you are getting nowhere with the individual on the phone ask to talk to another tech. My conversation went " Hey Tim, I appreciate talking with you and your professionalism but I feel I need to talk to someone else, is a higher level tech or your supervison available? Again I appreciate what you have tried."
In my experience with Comcast I have found that as the nations largest ISP, they grew too big too fast, with little regards to reliability.
A customer used them at a time share in Vero Beach, Fl. All of a sudden I couldn't get to the router and my office was 40 miles away. The internet was down and the management office had over 200 calls about the internet being down. I drove there and found the router settings wer still set as per the network diagram. I rebooted the router, no luck. After talking to everyone and their brother (Over 5 hours) at Comcast, finally Jose the guy who actually knew networking, helped me get back online in less than 30 minutes.
What happened was the modem was originally set so thestatic router and block of static IP addresses would work for remote access were suddenly changed to dynamic. He explained that they just upgraded their network management system the night before and unfortunately we were a victim of poor planning.
In the end I sunk the business with a bill for $700 for my time and they were furious! I explained that Comcast's horrible customer care was to blame, not me!!!