Vodacom Data rip-off

Whenever my data runs out, I buy additional bundles. On 2 occasions (July and August) I was billed in excess of R4000 per month for data used out-of-bundle. I was either not notified of my data being depleted, or my additional data bundles were not loaded. I lodged a complaint at Menlyn customer service which Vodacom is investigating???<br> What is there to investigate? It's obvious from all the complaints that many people are being ripped-off by charging these crazy fees for data usage which they are not aware of or data that just disappears.