A strike at South Africa’s port and rail operator Transnet SOC Ltd. that’s cost bulk mineral exporters as much as 9.8 billion rand ($538 million) continued for a 12th day, with the company and labor unions struggling agree on wage increases.

The walkout by workers that began Oct. 6 cost shippers of iron ore, coal, chrome, ferrochrome and manganese about 815 million rand a day because they’re unable to rail and load the exports onto ships, according to the Minerals Council South Africa.

“There is limited export from harbors” and rail movements are severely constrained, Allan Seccombe, a spokesman for the lobby group, said Oct. 17 in a response to questions.

Negotiations to reach a pay deal have been unsuccessful, even after the government and an arbitration body joined the discussions between Transnet and its biggest labor unions. The virtual shutdown of South Africa’s monopolistic logistics company has taken a broad toll on not only mining and agricultural exports, but service businesses and others involved in supply chains.

“Parties are still engaging,” Transnet spokeswoman Ayanda Shezi said in a reply to questions.

“Members are still on strike,” Amanda Tshemese, a spokeswoman for the South African Transport and Allied Workers Union, said by phone.