The Public Servants' Association (PSA) has given President Cyril Ramaphosa and his government seven days to respond to its demands, or face a national shutdown.
Scores of union members marched through the streets of Tshwane on Thursday, before handing a memorandum of demands to the Treasury department.
They are demanding a 6.5% wage increase, after the government implemented a 3% baseline increase in October.
PSA president Lufuno Mulaudzi accused the government of being "very arrogant".
"When they took power in 1994, they claimed to be a government that listens to its people. They said they are a government of the people.
"They are not the government of the people. We can't tolerate this nonsense. We have been warning them about their attitude. Their attitude is a threat to collective bargaining. In 2020, they reneged on the 2018 resolution," he said.
Muladuzi lashed out at Ramaphosa, claiming he promised to establish an independent body to assess wages for public servants.
“An independent body established by Ramaphosa can't look at the public service wages. We have the Public Sector Coordinating Bargaining Council looking at labour issues, including salaries of public servants.
"If he appoints that independent body led by a judge, we will fight with the government. We are not backing down. This [march] is not the end of it."
The union has given the government seven days to respond to its memorandum.
"We are going to shut this country down. We are going to shut down every office. Those sitting at home thinking the strike won't happen, they will join us when we meet next time," Mulaudzi warned.
"The PSA expects our demands to be favourably considered by Ramaphosa. We expect to receive a response in seven days to avoid any further or increased action and mobilisation by PSA.
"We have shamed our enemies. They thought this march was going to be a flop. Wherever they are, they are ashamed. Unfortunately, the Presidency is not here. It is very disrespectful to the PSA."
Mulaudzi warned the government to refrain from sending junior officials to receive their memorandum.
"We can’t have a situation, when we need the president, [he] is not here. He has sent junior officials to accept our memorandum. We expected to have the director-general receiving our memorandum.
"We have a single-term agreement for the years 2022 and 2023. We agreed after the employer had shown that they can't be trusted with the multi-term agreement. The government has reneged from implementing a negotiated three-year agreement in 2020."
Mulaudzi said the government's failure to implement decent salary increases for public servants was the result of years of unabated fraud and corruption.
The PSA claims its members are being crippled by rising inflation, escalating fuel prices, food, transport, and interest rate hikes.
"Public servants are expected to render services without receiving pensionable salary increases for the past three years. We demand protection of cash gratuity beyond 31 March 2023.
"Some of our government workers are scared that if they don't come out and join our march, they will have their salaries deducted. They don't know that come 32 March 2023, they won’t have that R1 000 they are budgeting for," Mulaudzi said.
'Government is playing with us'
Meanwhile, more than 500 PSA members and affiliates protested in the Durban city centre on Thursday.
They were joined by a small group of Health and Other Services Personnel Trade Union of South Africa (Hospersa) members.
The PSA's national director, Nondumiso Mvubu, said they were frustrated with the government's failure to provide adequate salary increases over the past two years.
"We have not had a decent wage increase. We want to make an impact and show government they are playing with us by not giving us any increase," she said.
Mvubu said a 3% increase was disrespectful and well below inflation. Statistics South Africa recorded headline Consumer Price Inflation at 7.5% in September.
Hospersa natio...