Unfair practice by vodacom

My name is Philip. I recently took out a data contract with vodacom. The problem i'm experiencing with them is that my data that is expiration within 2months depleting first, and the data that is expiration in one month is being used last. Which means i will never be able to carry data over.I call them and send them messages on messenger, i explain to them the problem and they told me that it should not be like this. The problem is that this is still happening. I try to warn others about this *****ed practice of vodacom but they are blocking me on their platforms like facebook.