The honest truth is that you can't force a company that controls an asset to charge a particular price or price it in a particular way without giving total control over that industry over to the government: A move that rarely if ever serves to work out well for consumers since the government's favorite company, IE the ones that contribute the most -Like AT&T- Tends to end up taking over the entire industry and edging out all of their competition through regulation instead of competition. This is why in the utility and public transportation industries, even when demand is falling, overhead costs and pricing in those industries continue to rise, made up for by price gouging when demand returns due to conditions in the marketplace. These are extremely inefficient models of doing business compared to good old fashioned market forces and competition.
And that's the dirty secret here: The only way to punish AT&T for trying to quash content that competes with their own is for people to consciously choose the next best alternative until it hurts them so bad financially that they have to change their policies in order to earn their customer's business once again. If they get gutted financially by their competitors, they may offer a better product to try to compete or simply get obliterated by newer companies with better ideas.
The only reasons why people grow restless and look to government to carry out this process for them in the modern era are as follows: First, because they don't know any better and don't realize they'll be worse off for putting idiots that know nothing about economics in charge of industry. But also because AT&T is the 6th largest company in the world with many of their competitors close behind. It takes a serious bludgeoning in the marketplace to cause any of these companies to move because their revenues and influence over their own market is significant. This means that real change in the market place can take 4 to 5 years of consistent hammering and discontent to level the biggest shareholders in the marketplace. But customers, in the end, are the most powerful participants in the marketplace. AT&T being huge means huge revenues but it also means huge overheads and costs that cannot be easily jettisoned in the event their revenues drop off. This translates to HEAVY losses in the even of any significant downturn in business. If enough people decide definitively that companies' services like Netflix are more important to them than the convenience and other advantages of having AT&T internet services, people will switch to whatever they can get and cause them or one of their competitors to eventually bring to market the products that will replace data capped internet connections.
Era demonstrandum, Comcast has already taken significant steps, from what I've been told, to remove the data cap on their connections to avoid hemorrhaging any more customers!

It can be done, just trust the free market and hang in there, my friends!