The Dongguan City Labour Bureau has released the names of 15 companies that have failed to comply with the law (see list here - in Chinese only). Of the 15 companies, 12 owed wages (with more than 100,000 yuan owed in 10 enterprises, and more than 400,000 yuan in six; one enterprise owed 1.337 million yuan). Two used child labour, six had not signed labour contracts with employees, while others had paid below the minimum wage and failed to comply with maximum work hours legislation. You can see more here (in Chinese only).
The companies were involved in toy production, plastics manufacturing, bottling water, and so on. Some where Hong Kong, Macau or Taiwanese-invested enterprises.