Vodacom Cheating

I am on Smart XS package with Vodacom, 50 minutes airtime per month. What you do not use gets carried to the next month and you are allocated with your new 50 minutes. But now they are very shrewd because they do not use the carried over minutes firstly, but in fact first use the new airtime and thereafter the carried over’s. If you do not use it, you lose it. It expires!!! This is totally unacceptable and cheating. I payed for the airtime. If one fill up your vehicles fuel tank at the beginning of the month and one does not use it at all, you do not lose it at the end of the month. It remains in your tank until totally used. Data they have changed, why can’t they do the same with airtime? The government must step and stop this *****ing from customers. They are very quick to phone or message one reminding to pay your account otherwise your service will be suspended, but in the meantime they *****!!!