Drained airtime. Not the first time!!

<p>This is not the first time it happens and I thought the problem was fixed but I have bought so much airtime only for it to be drained. I use wifi when I am at home and buy power hour to save costs. I have time and again found my airtime depleted. I spoke to several other vodacom subscribers and they said the same thing was happening. I am not very pleased at all. So are we supposed to switch to contract so I that we done get taken advantage of? I am honestly really tired of this. I can't be complaining time and again about the same thing. Thank you </p>