Disappearing airtime - Mtn not willing to assist

I have loaded airtime multiple times in the last few days, only to have it disappear within minutes. On multiple calls to the call center I get the same generic response - its automatic updates and internet usage and that's all the information they can give. I've told the same story again and again - I've switched of all mobile data and I've ensured auto updates are off, and still my airtime disappears. I'm tired of not being believed when I say there is a problem here. <br> <br> I was told to go into a store, I did so, I was told by the store only the call center can help. So who can actually do something at Mtn? Every avenue I try I am met with the same attitude of passing the responsibility on to someone else because it is seemingly too hard to actually provide a useful service to your customers. You have a problem here, I am not the first person to report disappearing airtime, and most of us do know how to switch the data off on our phones, believe it or not. It would most useful if you could actually investigate this.