The bad customer service I think is a reflection of the bad practices internal to comcast. Unless Amazon uses their might to leverage comcast to upgrade their network etc, they're just going to be a friendler face ontop of a bad service.
I suspect the support issues are mostly a result of Comcast trying to save as much money as they can on that front. Supporters never want to spend the time figuring out what's wrong: they want to end the call as quickly as they can, and probably hit their quotas.
The customer service is definitely atrocious. I remember one incident where the modem was clearly indicating that it wasn't seeing a signal on the line. I called up, and the guy asked me to reboot my computer. I explained that this was clearly unnecessary, and he agreed and proceeded with proper troubleshooting. Then at some point he must have forgotten and reverted back, and asked me to reboot my computer again! It was bizarre.
Worse was when they had to send techs out. They give four-hour windows and then never even make them, nor do they ever communicate to tell you they're going to be late. I had one guy show up at 5PM for a 12-4 window and then act baffled at why I wasn't there. When I did manage to make contact, they often sucked. One guy did some work on my exterior wiring and then just left without cleaning up. I went outside to find open cable boxes, wiring sticking out, and bits strewn around on the ground.
Things got better when I discovered the @comcastcares account on Twitter and started telling them about the ridiculous stuff that was happening. But it shouldn't even require that.
Now I have FiOS. I've had to call for a problem exactly once. That one time, I got a person and told them that I logged into the router and it said it couldn't obtain a DHCP lease from Verizon. This tech understood exactly what that meant (I never had a front-line Comcast tech understand "DHCP") and immediately launched into appropriate troubleshooting. She had me back online in a few minutes with no bullshit.
Speed issues still aren't resolved, but it's tolerable now.
Always sign up for business service when dealing with Comcast.
Occasionally at night there are disconnections.
But the customer service is definitely awful. I find I have best success immediately asking to be transferred to the customer loyalty office rather than the call center.
I'd honestly love to see Comcast try to fuck with Amazon, and then the frantic backpedaling as Bezos throws a thousand lawyers at them.