After a year-end customer audit, some Comcast customers report they are now being notified by the cable company they were not charged modem rental fees in error even though they previously purchased their own equipment.

“Late last year, I received a form letter from them notifying me that they had noticed that I wasn’t being billed for the modem they claimed they were renting to me,” wrote a Reddit contributor. “An hour-long phone call with four representatives later, the $8 charge was removed. However, it seems that since they increased the modem rental fee to $10 per month, they’ve brought my modem back into their flock.”

He isn’t alone.

Another customer found Comcast still billing him for a modem he returned to Comcast three months earlier.

“I’m now on my third month where I had to call, get a refund, and get a promise it won’t happen again,” wrote another Comcast customer.

The customer service representative argued the charges were valid, despite the fact the customer went to extraordinary lengths to document the return of the equipment to avoid being charged for it. Instead of claiming the customer never returned the modem, Comcast registered the customer’s newly-purchased modem as Comcast property.

“It shows that modem is with the customer,” said the confused Comcast representative.

“They are that s****y of a company, I saw this coming from a mile away,” said the customer, who recorded the return of Comcast’s modem in a video he made at the local XFINITY store. Despite that effort, he was unprepared for the possibility Comcast would unilaterally adopt his new equipment and claim it as their own.

Watching your Comcast bill like a hawk for unauthorized charges can also get confusing when Comcast keeps changing the name of the fee.

Customers with their own modems should find no charge for modems, gateways, or routers on their bill.

“I had to make three calls, each one more and more frustrating,” another customer complained. “The first was to remove the equipment fee, the equipment fee then morphed into a modem fee [… and the] final call was when the modem fee evolved into a router fee.”

One Comcast customer complained on the company’s own support forum he was charged modem fees for over a year for a modem he purchased himself.

“I have gone through customer service both on the phone and through chat,” complained the customer. “The charge will come off for a month and then get put back on my bill. I even went through Comcast Corporate Escalation and it was removed in October 2014. I went back through my bills and noticed that the charge went back on the very next bill and I have been charged ever since.”

To add insult to injury, Comcast now also bills a “change of service fee” to remove the erroneous charge, only to have it return the following month.

Because Comcast billing errors are so common, still another customer shared some tips on how to prove Comcast customer-owned equipment does not belong to the cable company.

“My advice if you are thinking about buying your own modem is to make sure you file all receipts,” said the customer. “I went through this same runaround with Comcast last year and luckily I still had both the sales receipt from Amazon as well as the Comcast document stating I had turned in my rented modem. It still took a few phone calls and a week or so for them to straighten it out. Pretty ridiculous.”