Telkom charging extra for unlimited contracts

I have 3 cellphone contracts with Telkom plus as Wifi Router contract. I took out unlimited cellphone contracts with Telkom Mobile 3 years ago which means we had unlimited calls and unlimited date. As from this month Telkom decided that we only have 3000 minutes anything there after we pay for the call usage so Telkom is charging me a R 1 100.00 extra this month for call usage which I never signed or agreed upon. I only signed for unlimited contract which means unlimited calls and data. Telkom just decides to changes things as they want without informing their customers.