Data usage

Vodacom has been consistently getting away with high data charges and now data is simply taken. I got a message after saying my data has depleted THEN one after that saying I have 4mb left. incidents when i purchase power bundles, such as 100mb , they run out while downloading a 70mb file. No apps were running besides whatsapp and no media was being sent or received. It's as if you're being forced to continue buying more data . I bought the 30 day bundle so there are no hourly promotions. my roaming is off, there is no logical explanation why this happens once in a while. i do not call customer services anymore because they will continue to blame \possible running apps"as if I am not knowledgeable enough to understand my phone. I am now changing networks after 10 full years with this network"