Don't honor contract deals

I have moved my cell contract from Vodacom to Telkom due to the fact that their deals is better than other networks. I bought vouchers last month to the value of R140 that is equivalent to the Free Me 1.5GB deal. I then selected the option on the phone and I was allocated (1GB Data, 250MB Data for WhatsApp, 250MB data for streaming, 500min on net call minutes, 25min off network call minutes, 100SMSs). my problem is that whenever I phone a number on the on net network it doesn't go of on that option but on the money that you buy if your off network minutes is finished. Please help