Greedy Vodacom

Yesterday, I recharged my Vodacom account with R29 airtime. Then I bought 100mb 7-14 days for R16. This morning I receive a message stating that I have 25mb remaining. I switch off my mobile data and then receive another message stating that I have 9mb left and then another simultaneously, stating that my data is depleted. Bare in mind that my mobile data was off. I try to make a phone call and I'm told I have insufficient airtime. I don't even understand how that is even possible because I was supposed to have R13 airtime remaining after my data purchase. I am so infuriated right now because 100mb depleted overnight AND R13 airtime too. I'm sick of this.