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 firm says, and the company is required to pay $2,000 to each person involved in the lawsuit and whose smartphone was impacted by the slowdown.

Battery replacement program

Apple admitted in late December that it slowed down older iPhone models with degraded batteries in an attempt to prevent unexpected shutdowns.

“Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components. Last year we released a feature for iPhone 6, iPhone 6s and iPhone SE to smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions,” Apple said.

The company kicked off a battery replacement program in early January with a discounted price to $29 for the repairs performed this year.

It’s been reported, however, that Apple has a hard time dealing with all battery replacement requests, and some appointments have been pushed back to March and April due to the constrained battery inventory.