Thousands of angry users saw data bundles and airtime disappear before their eyes overnight.
On Tuesday morning Vodacom spokesperson Byron Kennedy said the problem was caused by a configuration change on their billing system.
Vodacom vowed to make sure all its customers are reimbursed by the end of the morning.
TechCentral Journalist Duncan McLeod chats to Stephen Grootes about Vodacom's disappearing data.
He says Vodacom told him they were doing a system upgrade that turned out to be 'problematic.'
It affected 'top-up' and prepaid customers, not those on contracts, he adds.
Take a listen:
This article first appeared on 702 : Vodacom claims system upgrade caused disappearing data