Comcast can146;t fix it, I am at my wits end!

This has been going on for about 3 months now, the browser thinks it is loading something but waits indefinitely. The modem is connected to something and says there's internet, but there is none. This happens maybe 6 times a day for 45 minutes on end. The rest of the time internet is spotty and slow. I can’t stream music because it is always buffering, always. We pay top dollar for 20 megabit downstream. They forced me to buy a new modem before they would even send a truck out, but that was wasted money. Comcast has sent 3 different crews to our house 3 times in the last 6 weeks and it still isn’t fixed. Last week a local technician called on the phone and said there is a known issue with the wiring on our block. Today a technician looked me straight in the eye and told me its not Comcast’s fault. In the next sentence he told me I have to rent a modem from them or they can’t fix it. I am fed up and need some reliable internet. Now seriously considering going back to the Qwest DSL, which is slow but at least its on all the time. Sorry for ranting, I am at my wit’s end.