People are furious about subscription fees for one of the most-anticipated fitness apps

Kayla Itsines is a social media and fitness star.

The 24-year-old Australian behind the Bikini Body Guide has legions of fans and over four million followers on Instagram.

But now, People is reporting that her fans are furious because her app, Sweat With Kayla, is charging them unexpectedly and that the subscription fee is nearly impossible to get out of.

People claims that clients are downloading her app for a free 7-day trial, but that they have to enter their credit card info first. If they don't cancel, they'll get charged $19.99.

Here are some reviews from the iTunes store. Common complaints include the app's price, recurring charges, and bugs in the app. Some people don't seem to mind.

When it was released in the fall, The Daily Mail reported that her fans called it "overpriced" and "a slap in the face."

"As always, we have the interests and wellbeing of our fitness community at heart and welcome contact from any of our customers should they require assistance from our team at any time," Itsines's representative, Bec Sealey, told The Courier Mail (via Racked).

Subscription services are often subject to criticism. Several retail companies have come under fire for recurring charges, such as Fabletics and Adore Me.

That said, there are still scores of positive reviews for the Sweat With Kayla app, and Itsines has plenty of loyal fans.

Business Insider has reached out to Itsines's team and will update when we hear back.