Disappearing data 1.1gb in 10 minutes with mobile data switched off

Dear Vodacom

I have a data plan with Vodacom and was advised I had run out of data so I purchased a 1GB data bundle at your absurd rates and received confirmation that it was loaded and my Data balance is 1.1GB. Ten minutes later I get another SMS that my data has been depleted and I will be paying out of bundle rates. The most interesting part is that mobile data was switched off on my device and I was connected through Wi-Fi only, so again Vodacom is busy ripping me off, I am going directly to the CPA this time since I have never had a pleasant Vodacom experience. I expect to get what I pay for and not get ********** with it disappearing while mobile data is off and the worse your expiring data, if Vodacom buys bread and doesn't eat by a certain time does the shop come and take back the bread you haven't eaten even though you paid for it? Absurd supported theft.