Apple has abused its dominant position by charging app developers an unfair 30% commission through its App Store, costing British consumers up to 1.5 billion pounds ($1.8 billion), a London tribunal heard on Monday.

Apple is accused of overcharging consumers for software sold via the App Store in a £1.5 billion class-action lawsuit bought by Rachael Kent-Aitken on behalf of 20 million UK consumers. (That equates to about $1.8 billion in US dollars.)

Apple is under trial at London’s Competition Appeal Tribunal, accused of exploiting its dominance by overcharging app developers a 30% commission through its App Store. The lawsuit, representing 20 million UK iPhone and iPad users,