Apple is being sued in Great Britain because the tech company would have overcharged consumers for purchased apps.

The plaintiffs, led by a professor from King’s College in London, argue that the 30 percent commission that app developers have to pay Apple is “lavish” and “illegal.” iPhone and iPad users should therefore be compensated.

According to professor Rachael Kent, who specializes in the interaction between consumers and digital platforms, Apple is abusing its market power with the demands placed on software companies. “That, in turn, has negative consequences for British consumers.” According to the indictment, some 20 million British Apple customers have been harmed by Apple.

Apple says the claim is unfounded. The company says it stands firm for consumers and has created a lot of value with the App Store and the British economy. Furthermore, 84 percent of app developers would not pay anything because their apps are free. The remainder may qualify for a 15 percent commission. Apple recently lowered rates for some of the apps that meet certain conditions.

The case comes as Apple is defending itself domestically against allegations by games maker Epic that Apple is running its App Store as a monopolist. According to Epic, Apple has too much power and is making unjustified demands. The European Commission has also questioned some of the provisions of the App Store and argued that Apple had abused its market power to disadvantage other music streaming services compared to its own Apple Music service.