Upgrade - double billing on devices

I received a message from Telkom stating that my upgrade was due from September, i took the upgrade on Saturday 2 September. In September I was billed for my old contract. Now in October I have been double billed for my new contract. Apparently paying the device fee for both September and October for the new phone. I have now ended up paying for both the old phone and the new phone for the month of September. Literally day light ******* and exceptionally ********* to offer a loyal customer an upgrade and then make the unfortunate person pay for two devices in a month. I can't understand how regulators allow mobile operators to even attempt to get away with this type of behavior.