Eskom is still trying to stabilise its online vending system used by pre-paid electricity customers.

Last week millions of pre-paid users could not buy electricity tokens anywhere.

On Friday the system went back online but the power utility yesterday reported it was still having some glitches.

"We're making progress in stabilising the system but we are still experiencing intermittent problems," said Eskom spokesman Hillary Joffe.

She said there were "issues" with the online vending system late last year.

"In November and December we did a lot of work on the system and upgraded the infrastructure, and from December until last week the system has been performing well," she said.

Last week Eskom CEO Brian Dames called on consumers to reduce electricity demand by 10%.

"We do not want to go back to load-shedding, but we cannot do this alone," said Dames.

Joffe was quick to dispel assumptions that the "IT problem on the central system" had anything to do with a shortage of electricity.

Eskom has six vendors. The vendors sell electricity to about 10000 outlets around the country.

The power utility supplies about 40% of households, most of which are on the pre-paid system. Municipalities supply electricity to the remaining 60% of homes.

Joffe said 4million Eskom customers use the pre-paid system, most of them low-income households.

She said the system was "very slow" on Wednesday afternoon. The situation deteriorated and on Thursday morning the system crashed and was inoperative for several hours.

"We did manage to restore it within two hours but throughout Thursday afternoon there were issues all over the place," said Joffe.

"We decided to shut the system down altogether on Thursday night to get to the root of the problem and make repairs.

"Our IT team did some major work on the system," she said.

By Friday everything was up and running again.