Comcast cmcsa has reportedly moved some networks to more expensive tiers—a change that means some customers will have to pay more to continue watching their favorite channels.

Viacom-owned channels Spike and CMT, and well as Pop (formerly known as the TV Guide Network), are being moved to higher-end packages, in a move that Comcast says is a response to increasing programming costs.

But Viacom viab said in a statement that that it has some problems with Comcast’s decision. “This action is in direct violation of our agreement and will increase costs for customers who will now have to pay more for networks that were previously included in less expensive packages,” Viacom said.

Viacom maintains that “all the extra money from these higher monthly fees goes directly to Comcast and is not shared with Spike TV or CMT.” A spokesperson told Fortune that any programming price hike is the result of a long-standing contract with Comcast, and that the two networks cost less than a penny more a month in total than they did last year.

A Comcast spokesperson disagreed, telling Fortune that it has contractual rights to move or even drop channels. “Our goal is to provide customers with the best value and most viewing choices,” Comcast said in a statement. “However, due to increasing programming costs, we sometimes need to make adjustments to our channel lineup. These are not easy decisions, and we know that some customers will be disappointed.”

The spokesperson added that most Spike viewers already have the more expensive package that the channel is being moved to, so those viewers won’t face additional costs. But plenty of Comcast customers have taken to Twitter in protest:

Comcast’s programming costs, which it expects to hit around $10 billion for 2015, have doubled since 2006.

This article has been updated with additional information.