Comcast is being forced to pay the largest fine the FCC has ever levied against a cable operator. Its offense: Charging customers for services and equipment they didn't ask for.

The company agreed to pay a $2.3 million civil penalty and to submit to a "compliance plan," in which regulators will monitor Comcast for the next five years to ensure it cleans up its act.

"It is basic that a cable bill should include charges only for services and equipment ordered by the customer -- nothing more and nothing less," Travis LeBlanc, chief of the FCC's Enforcement Bureau, said in a statement.

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The FCC said it received over 1,000 complaints from customers, who said Comcast charged them for premium channels, cable boxes, DVRs or other products that they never ordered.

In many cases, the FCC said, customers expressly told Comcast that they didn't want the add-on options, but they were charged anyway.

Complaints also describe how customers spent "significant time and energy to attempt to remove the unauthorized charges" and get refunds, the commission said.

The complaints spurred the FCC to launch an investigation nearly two years ago. Today's settlement marks the conclusion of the probe.

Under the five-year compliance plan, Comcast must begin sending customers special notifications every time a new charge or service is added to their bill. The company also has to add a way for customers to easily "block the addition of new services or equipment to their accounts," according to an FCC press release.

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Comcast (CMCSA) will also be required to compensate or address complaints from customers who have disputed charges, and it will be barred from referring an account to collections or suspending an account that has a disputed charge.

Comcast agreed to the fine without admitting any guilt.

The company did say Tuesday that the complaints stemmed from poor customer service or human error, and not a "problematic policy or intentional wrongdoing."

Comcast added that the issues were due to "isolated errors or customer confusion," according to a statement. "We agree those issues should be fixed and are pleased to put this behind us and proceed with these customer service-enhancing changes."