The problem with the internet, especially cable, is that it is a natural monopoly. It's like most utitilities that require infrastructure to the home. It would be stupid to have 10 competing water companies, right? That's because there would be large amounts of redundant infrastructure. Therefore, it is better to have a highly regulated monopoly with pricing set to prevent monopolistic rents.
The current situation is that each cable company has a monopoly in most areas, with DSL providing a duopoly in some places. Obviously, monopolistic pricing occurs, with prices far above the free market rate for inferior service. But that isn't illegal! You have to show that they are acting in an anticompetitive manner, which is very difficult.
Even in the case of oligopilies, price fixing is legal as long as it is implicit: A company can signal to another by unilaterally raising prices in a way that would be irrational if non-cooperative behavior is assumed. Then the other company will raise their prices as well, to acheive a cooperative outcome with both companies making more money. Again, this isn't illegal, unless there is an explicitly communicated price-fixing agreement.
Thus, FTC antitrust stuff means fuck-all.