MTN refuse to give my unused data back which I already paid for

They continue playing games, I will take this to the consumer council. My unused 10GB data was supposed to carry over as it does monthly but they took 3GB of that and refuse to give it back. They actually made the mistake by telling me anytime data bundles carries over for two month's in that case they took 5GB of my data and not 3GB. I know my contract and I know my rights. I'm going over to Vodacom with Fibre which is excellent then I don't have to deal with people that don't know what they're talking about.