Telkom insufficient fund even though I didn’t use it

I recharged with R18 to buy data, when i tried purchasing, i got an sms saying “insufficient funds” and that the balance was now R6.55, yet I didn’t buy, call or even have my mobile data on. This is neither the first nor 2nd or 3rd time, it happens ever so often and every time i lay a complaint I get the same story that My airtime got used at out of bundles, how??? My data wasn’t even on, so they just magically siphon the airtime whilst everything is off? They never take accountability, even when i show them proof that, they offer zero assistance. Im fed up.