Poor service vodacom

Bought 100mb of data on the 9th of april and got a sms on the 19th of april saying my data has run out. Strange thing i monitor my data usage on the phone and it was set from that day and till the 19th the phone indicates only 57mb was used. I dont use the phone and all updates are blocked. All inclusive apps used 57mb, so where is my other data?????

Sad part is customer care didn't care much and didn't even try and help only saying you have been billed right and to take phone to vodashop....

Im a technical guy and this doesn't add up. Data is running out and i feel vodacom is doing me in even after being a long time customer, this is not the first bad experience i had with them also.....

Thinking of changeing network once and for all!