*****ing what I've paid for

If I could give 0 stars I would! I cancelled my contract with Telkom, but I still had data left on the sim. They immediately took the data away from me even though it was paid for in full. Correct me if I'm wrong, but if I pay for something it means it is mine right?! And if you take it away from me without compensation its *****ing right?! I will go out of my way to discourage others from using anything Telkom related.