Eskom’s pre-paid electricity vending system was back on line on Friday, after it went down for an hour, spokeswoman Hilary Joffe said.
She said the system was still slow in areas and some customers were unable to purchase electricity.
"We do apologise for the inconvenience caused, we are looking carefully at the issue," she said.
She said last week that the system was slow and an investigation had been launched to find what was causing the problem.
