Vodacom has not revealed what caused an error that led to several of its customers being double debited last week.

Vodacom sent an SMS to customers on Friday afternoon informing them that the company was aware that some accounts had been debited twice owing to a “technical glitch”.

The company promised to reimburse affected customers by the close of business on Monday and it apologised for the inconvenience.

But Vodacom representatives on Monday did not answer questions about what exactly caused the glitch last week.

A Vodacom spokesman said the company cannot reveal how many customers were hit by the technical glitch. Vodacom is South Africa’s biggest mobile network with more than 30m subscribers.

On Monday, the company said in a statement that it was working to resolve the problem by the end of business hours.

“Where debit orders were processed twice, Vodacom is working on ensuring that refunds and all associated banking charges are paid by close of business today at the earliest,” Tshepo Ramodibe, Vodacom’s executive head of corporate affairs, said by e-mail.

“We are in the process of refunding the customers,” said Ramodibe.

Vodacom customers have also turned to social media on Monday to find out exactly when they will be reimbursed.

In response to one customer, Vodacom’s official Twitter account said that customers’ refunds would be processed on Monday “due to the banks being closed on the weekend”.

Vodacom is not the only major South African company to suffer technical glitches in recent months.

First National Bank and Standard Bank suffered glitches last year that affected services such as online banking.

Meanwhile, Unternet services, contact centres and shops affiliated with telecoms company Telkom were briefly offline on 18 May last year following a network switch failure at one of its data centres in Centurion, Gauteng. — Fin24