The problem is that AMERICA'S internet infrastructure sucks, and Comcast is a member of the group running our incredibly piss poor network. TelCo's had no reason to even try until a couple of years ago, and Google's attempts to buy the old TV spectrum for nationwide wi-fi got screwed up (like it or not, it would have at least improved the chances of fixing things nationwide, especially in rural areas).
Comcast is a behemoth. They don't know what one thumb is doing on the same hand, let alone what their other arm is doing. I've had Comcast for 12 years. I've been able to get promos for 11 and a half of those. Six months they just wouldn't do it. Now I'm under a promo for $39 a month for internet. It's good service. The service is about as good as you're going to get if you don't live in a Google fiber town or something comparable. But it's the billing that is a mess. Flat rate it at $29 a month and everybody would sign up. Instead they try to nickel and dime you to death and the rates jump one month and they hope you don't notice. My mom's bill climbed from $60, to $90 to $139 since December. I've fought with them numerous times about her bill and get promised credits and then she melts down. I tell her to cancel it, and she panics. It's really silly stuff. But they seem to enjoy just trying to scam people.
If you don't mind dedicating a weekend a month to dealing with your bill after your initial promo and fighting for a rate decrease and threatening to leave (and even leaving for periods of time) then enjoy. It's a good service with terrible service if that makes sense. I bought my modem off of Amazon for like $49, so no monthly rental. The installer just activated it in my new home by typing the MAC address into his little device he had hooked up to my cable while getting it going. Just make sure it is compatible with Comcast. They will get it going and off they go... to scam another.
R.I.P. Dad. I miss you. You will never be forgotten
1/12/39 - 8/7/08