Data & Airtime vanish

This is going on for some time now where the one moment you have 50mb left & when you look again, there is no airtm or data, i just bought R12 Vodacom, and i did had data left, i bought 30min vc 2 vc for R5, than i wanted to check my dstv balance but it sad i have insufficient funds, when i checked it was R0.00 . Vodacom have a complaints page on facebook, but they dont even bother to reply. The adverts, etc is just a money making scheme to milk poor people.