If so, you may have some money coming to you. Those lying, cheating, scum just lost their last-ditch appeal in front of the Supreme Court of South Korea.
For those not in the know, what Chung Dahm Institute (aka CDI) had been doing was falsely listing their foreign employees as independent contractors. This had the benefit–for CDI, of course; not for the employees–of relieving the franchise owners of paying for such niceties as national health insurance, national pension scheme, and severance to etheir employees. It took some years for the case to wend its way through the Republic of Korea’s legal system and it finally came to an end on 11 June 2015, a day that will live in fame for native English teachers in South Korea. Mind you, other hagweon (foreign language academies) chains have been, and still are, pulling the same stunt as CDI; it’s just that CDI has been the most egregious offender.
If you worked for them, please contact a lawyer in South Korea as soon as you can. Of course, there is a statute of limitations involved–sorry, I don’t know what it is for this case.