Vodacom ***** with PrepaidPlanBonus awards

When buying prepaid airtime through the bank we get a sms to say that an equal amount has been allocated as a bonus until midnight the day of the purchase. However I have noticed that this bonus is NOT used when making calls. The previous time I noticed this I complained and the money was refunded a few days later. Today we recharged and made a call, and the SAME HAPPENED AGAIN! The call was charged to normal, not bonus airtime. I called customer services who said - NO, you need to switch normal data off first! Even though this instruction is NOT on your website I retried, but the additional call was still taken from normal not bonus airtime. Vodacom are **********ly taking money from customers by misleading them about supposedly prepaidPlanBonus calls.