Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

If you've cruised around Amazon, eBay, and many other popular websites, you may have noticed an unusual number of images have been removed from listings. In their place: An image asking the user to upgrade to a $399.99 account in order to enable third-party hosting.

That's because Photobucket, a photo sharing service, quietly changed its terms of service, demanding a yearly fee from users who want to post to other sites. Customers have lashed out, accusing the company of charging a "ransom."

Byers Market Newsletter Get breaking news and insider analysis on the rapidly changing world of media and technology right to your inbox. This site is protected by recaptcha

Related: What to Expect from Amazon Prime Day

Photobucket announced last week in a blog post that it was changing its terms of service. However, the post didn't mention the third-party hosting change. In order for users to find out, they would have had to have clicked the link and read the fine print.

Many users didn't find out until they noticed their images were no longer showing up on their third-party pages.

"I have been using your site for 10+ years & you gave ZERO notice. You screwed 178 of my eBay listings. You are extortionists," Twitter user @HitchensSKINS wrote.

No surprise @photobucket users are annoyed when the pricing change is hidden behind an advert that can't be closed and prevents scrolling. pic.twitter.com/pecKmdor5p — Andrew Smith (@meejahor) July 5, 2017

A little heads up with time to get my photos out of your site would have been appreciated. And $400 a year is ridiculous. — Elena LaVictoire (@mrsL) July 1, 2017

Hope you go out of business with this strategy. Not paying a $400 ransom, I'll find someone else to host my pictures. — Ms. Virion (@Pathogenome) June 29, 2017

Photobucket's team did not immediately respond to NBC News' request for comment. However, in a July 1 tweet, the company wrote: "Thank you for all of the recent feedback and questions. We are trying our best to respond quickly and thank you for your patience :)"

Nice way to out yourselves out of business Photobucket ;) keep up the good work! Maybe u will be bankrupt soon — Devin (@dgs2045) July 5, 2017

The Denver-based service was founded in 2003. The company says it has more than 100 million users.