Thousands of workers at the South African Post Office (SAPO) and Telkom downed tools on July 6 to demand higher wages.They are affiliated to three unions - the Communication Workers', Customs and Democratic Postal and Communications unions, GroundUp reported.The workers are demanding a 12% increase but SAPO insists it can only afford an across-the-board salary increase of 6% for all employees from August 1.The strike has left hundreds of social grant beneficiaries stranded.In Pietermaritzburg, beneficiaries were seen standing in snaking lines outside the post office in Langalibalele Street.Pay increaseNomzamo Khuse from Sweetwater had been standing in line since 05:00."When we came, the doors were closed. The employees told us they cannot help us. They said they have embarked on a strike. It's clear that we will go home without being paid."A post office employee who asked not to be named, said staff became upset because they have not received a pay increase in three years."There is an overload of work. We work overtime but we are not paid well. The work is strenuous since we are working with the beneficiaries. We open at 05:00 and go home at 20:30. It's more work but less money."Another post office employee, Jabulani Mtungwa, said: "We now service many people. That is a challenge. They need to improve the systems. They make working very difficult. We love our jobs but there are challenges. Look at these people [beneficiaries], they are frustrated and angry. Unfortunately, we cannot help them unless our issues are attended to."In a statement on July 6, SAPO urged beneficiaries affected by the strike to withdraw their grants at ATMs and other retail stores.SAPO will be returning to the Commission for Conciliation Mediation and Arbitration (CCMA) with union representatives on Monday.The strike is expected to continue this week, says provincial secretary of the Communication Workers' Union, Thami Mzileni.On Sunday, Mzileni told GroundUp that workers were planning to "shut down the CBD" on July 13. He said MTN employees were also expected to join the action this week.This comes as SA Social Security Agency (Sassa) employees affiliated to the Public Servants' Association (PSA) are expected to head back to the negotiation table with the agency after downing tools for nearly a month. They are opposed to the 7% pay hike agreement made with other unions. PSA members are demanding salary increases of up to 13%.Sassa again came under fire on July 2 when "a technical glitch" resulted in nearly 800 000 grant recipients not getting paid. These beneficiaries were among nearly 1.5 million people who have the new social grant cards distributed by SAPO.The state agencies assured grant recipients that the issue was resolved.SAPO took over the contract from Cash Paymaster Services for the distribution of social grants (excluding cash grants) on behalf of the agency in April.