Additional deductions after vc to vc voice purchases: Vodacom

I have observed a wired trend for some weeks I have been buying vc to vc airtime either the power hour or the Just 4u voice. I would get sms to inform me of the purchase and the balance available in my normal airtime. However the trend I have observed is that the next day my balance airtime would be depleted. One of the things I will do is normally check if I had made other calls which in all cases that this happened I had not made other calls to significantly deplete my airtime. After I noted this occurrence I made deliberate effort to monitor my call to check my balances the following day after I had made the vc to vc purchase. In all the instances my balances was depleted below what was the original balances recorded the previous day. My careful observation has led me to believe there is a deliberate trend and conspiracy of making additional deductions on the amounts of airtime after the purchase of vc to vc voice. This is to request vodacom to investigate this case that has occurred on numerous instances and refund me the deduction and losses occasioned by this trend.

Thanks