In a new letter from the New York attorney general's office, senior enforcement counsel and special advisor Tim Wu writes that Time Warner Cable has provided customers in the state with "abysmal" internet speeds, well below the "blazing fast" connections the company has advertised.

Letters says TWC "generally performed worse" than competitors

The office has been investigating internet speeds in the state since last year, and as part of that investigation, launched a tool in December that allowed customers to log their speeds. At the time, Wu — widely known as the father of net neutrality — told The Verge that the office was investigating whether companies' speed promises might be "illusory."

Data from that tool, Wu writes, suggests those concerns have a foundation. "Not only did Time Warner Cable fail to achieve the speeds its customers were promised and paid for (which Time Warner Cable blamed on the testing method), it generally performed worse in this regard than other New York broadband providers," Wu writes in the letter sent yesterday and addressed to Charter Communications CEO Tom Rutledge. (Charter recently bought TWC and plans to rebrand its services.)

"In short, what we have seen in our investigation so far suggests that Time Warner Cable has earned the miserable reputation it enjoys among consumers," Wu writes. "Overcoming this history will require more than a name change; it will require a fundamental revolution in how Time Warner Cable does business and treats its customers."