the news like to leave details when it comes to Iran.
korea didn't pay cause the thought Iran in sanctioned and don't have access to the banking system (swift), that they don't need to pay. thats was their excuse. but there are 100 ways to pay, it's not only bank transfer.
they can pay in gold like venezuela and turkey do, bitcoin, items (electronics etc.)... but they want to play clever.
here you can read in more detail about the frozen money and what south korea owes Iran.
Tensions between Seoul, Tehran mounting following Iran's seizure of South Korean-flagged oil tanker - Anadolu Ajansı
www.aa.com.tr