Apple will have to deal with one of the largest class-action lawsuits ever filed against the company, as more than 370,000 people in South Korea are suing the firm for making their iPhones slower on purpose.

Local law firm Hannuri Law called for all those whose iPhones were deliberately slowed down by Apple to join the lawsuit, starting in December with nearly 67,000 individuals and now reaching a record 370,000.

While Apple hasn’t commented on the lawsuit, Hannuri Law says in its legal action filed with the Seoul Central District Court this week that Apple violated local legislation requiring companies to share all details of software upgrades in order to allow customers to decide if they want to receive new updates.

By forcing iPhones to install new iOS versions that eventually throttled device performance Apple has violated these regulations, the …