Johannesburg - South Africa's Communication Workers Union (CWU) said its 2 000 members working at telecommunications operator MTN [JSE:MTN] would strike on May 20 to demand higher bonus payments.
The union is also demanding a 10% salary increase and higher remuneration for work done over the weekend and holidays. It also wants contractors turned into full time employees.
"Since March 12, workers at various MTN warehouses have been embarking on work stoppages to demonstrate their dissatisfaction over management's reluctance to address their concerns, in particular the issue of annual bonuses," CWU said in a statement.
The union said MTN was offering workers a 4% guaranteed bonus, whereas they wanted 16%.
MTN's spokesperson declined to comment on the strike but said the company had 6 500 staff in South Africa.
Some workers at MTN belong to other unions.
MTN shares were up 0.8% at 13:48GMT, outpacing a 0.5% rise by Johannesburg's Top-40 index.