The internet speeds provided by Time Warner Cable to its customers are "abysmal," according to senior enforcement counsel and special adviser to the office of the New York attorney general Tim Wu.

The company promises to deliver "blazing fast" connections, but subscribers are getting the opposite. Wu and New York Attorney General Eric Schneiderman are now hoping that Charter Communications will do more than rebrand Time Warner Cable.

Regulators cleared the $55 billion merger of Charter Communications and Time Warner Cable in April. The resulting company, to be named New Charter, will become the second biggest cable company in the country.

Time Warner Cable and Bright House, which Charter acquired along with Time Warner Cable, will be operating under the Spectrum brand.

In a letter addressed to Tom Rutledge, the CEO of Charter, Wu wrote that Time Warner Cable will need to have a fundamental revolution on how it conducts its business and treats consumers, and not simply a new name.

Wu added that the "blazing fast" and "super reliable" Internet connections being marketed by Time Warner Cable are false, based on a tool launched by the New York attorney general's office last December to collect internet speed data showing that Time Warner Cable was not able to provide the speeds that it promised to customers.

Time Warner Cable actually performed worse compared with all other broadband providers operating in New York, legitimizing the overly negative reputation that it has among local consumers.

Wu, a champion of open internet and the man who coined the term "net neutrality," investigated the speed of Time Warner Cable, Cablevision and Verizon, and while no specific figures were revealed due to the preliminary nature of the results, the early signs look very bad for Time Warner Cable.

Wu also said in the letter that he would soon contact Rutledge regarding proposals on the next steps for the issue now surrounding Time Warner Cable and its "abysmal" performance.

The investigation was spurred by the thousands of complaints that customers of Time Warner Cable have sent in to the attorney general's office, claiming that the download speeds promised by the company were not being met.

Time Warner Cable has previously called out supposed flaws in the tests which evaluate the company's network, and are not representative of the service that is being provided by customers. Other research conducted by the Federal Communications Commission found that about three out of every four customers of Time Warner Cable are consistently receiving within 95 percent of the internet speed that they paid for.