Airtime deducted for no reason

Vodacom has deducted airtime from my airtime balance for no reason! I had purchased a data bundle and even when the bundle was still active my airtime went from +-R120 to R0.00 and i still had remaining data available. I immediately contacted the call center and explained the situation only to be told that it was due to data charges which is impossible as i had data remaining. I asked to speak to a manager, who gave me the same excuse. The call was then cut off by the manager. I called back, the next consultant tells me that the system has not yet updated and information regarding today's interactions are not showing on the system which means the manager was lying to me and vodacom is *****ing airtime from customers. My wife had a very similar thing happen to her a few weeks ago and airtime keeps disappearing from her phone as well. We have a few lines with vodacom for many years. This is terrible service and if this is the case we would like to cancel all our vodacom contracts and take Vodacom to the correct authorities as this is theft.