Verizon isn't going to take an insult from Netflix sitting down.

The broadband company sent a cease-and-desist letter to Netflix on Thursday about a message Netflix has been showing some customers that blames congestion on Verizon's network for slow network speeds, according to a CNBC report.

Netflix subscribers have begun noticing that when videos stop streaming properly, a message appears on the screen indicating that congestion on an Internet service provider's network is to blame for the interruption. Vox Media designer and Verizon customer Yuri Victor was one of the first to notice the passive-aggressive dig: "The Verizon network is crowded now. Adjusting video for smoother playback..." AT&T subscribers spotted a similar message as well.

"We are testing ways to let consumers know how their Netflix experience is being affected by congestion on their broadband provider's network," Netflix spokesman Joris Evers told The Huffington Post. "At present, this is a small test in the United States that is not specific to any provider."

Verizon countered that the notification is "a PR stunt."

"We're investigating this claim but it seems misleading and could confuse people," Verizon spokesman Robert Elek said.

In a blog post Wednesday, a Verizon executive expanded on this idea, blaming any slow traffic on the secondary Internet providers that Netflix uses to deliver its videos to Verizon's network.

"The source of the problem is almost certainly NOT congestion in Verizon's network. Instead, the problem is most likely congestion on the connection that Netflix has chosen to use to reach Verizon's network," wrote David Young, vice president of Verizon's federal regulatory affairs group. "It would be more accurate for Netflix's message screen to say: 'The path that we have chosen to reach Verizon's network is crowded right now.' However, that would highlight their responsibility for the problem."

In the cease-and-desist letter sent Thursday, Verizon wrote that "there is no basis for Netflix to assert that issues with respect to playback of any particular video session are attributable solely to the Verizon network," according to CNBC.

When contacted for comment by HuffPost, Evers replied: "This is about consumers not getting what they paid for from their broadband provider. We are trying to provide more transparency, just like we do with the Netflix ISP Speed Index, and Verizon is trying to shut down that discussion."

This is not the first time Netflix has locked horns with Internet providers like Verizon and AT&T over deteriorating speeds for online videos. Each side thinks the other should pay for the infrastructure upgrades needed to better deliver the massive amount of Netflix data, which accounts for more than a third of Internet traffic sent to North American homes during peak evening hours. Netflix likes to subtly remind its customers of poor Internet speeds in the U.S. by ranking U.S. Internet providers each month.

Recently, Netflix gave in. It struck deals with Comcast and Verizon to grease up Netflix streaming on its networks. Net neutrality activists, who argue that all Internet traffic should be treated equally, have cried foul at Netflix being compelled to buy preferential treatment from Internet service providers.

Yet despite acquiescing to Verizon in the boardroom, Netflix appears to be winning the public battle. Internet service providers are the most hated companies in the U.S. out of 43 different industries, according to a survey done in May by the American Customer Satisfaction Index. The same group gave Netflix a higher customer satisfaction rating than every Internet service provider in the survey.