NBC is unwilling to run commercials for Dish's Sling TV streaming service on its own TV stations. Business Insider reports that Sling recently brought a new set of ads to all the major networks and their affiliates in eight cities. Everyone was happy to take them with the lone exception of Comcast-owned NBC, which rejected the commercials in key markets like New York and Los Angeles, where NBC itself owns and controls the local peacock station. The spots portray traditional cable operators as greedy and aggressive bullies, a sentiment that Comcast probably isn't too fond of. NBC confirmed the decision to Business Insider but hasn't detailed its reasoning.

"This is what Comcast doesn’t want you to see."

The move has irked Sling as it tries to market its internet TV service to cord cutters and young viewers who've shied away from cable subscriptions. "I was surprised that they would go to this level to block our commercials," Sling CEO Roger Lynch told Business Insider. Of course, a face-off like this also gives Sling plenty of exposure. NBC's now advertising for the service in headlines instead of on its channels.

In a blog post, Lynch wrote, "The refusal to air our campaign endorses the ads’ central truth: there are traditional pay-TV players that just don’t get it." Both Lynch and Sling's parent company Dish are painting NBC's decision as anti-competitive. "Comcast has a demonstrated history of shutting down ideas it doesn’t like or understand, predictably to its benefit and at the expense of consumers," wrote Lynch. Comcast is far and away the largest cable provider in the United States, and the company recently unveiled plans to launch its own internet TV service — though at a much smaller scale than Sling, which is available nationwide. Comcast's service, called Stream, will start out in limited markets and be offered exclusively to existing Xfinity internet customers.

With Sling, consumers can pay $20 per month for a base package of over 20 channels. More programming (including HBO) can be added for a monthly fee, and broadcast networks like NBC can usually be watched at no cost if you've got an antenna hooked up to your TV. Sling has refused to release official subscriber totals for its service, which launched early this year. In June, Recode reported that the company had surpassed 250,000 customers. That's tiny in Comcast's world, but apparently the company has no intentions of helping Sling grow further — even if it means rejecting advertising dollars.