Fed up with poor , shameful service

I upgraded my contract with telkom in june and the wrong device was sent to me , the device was returned to tekkom on the 27th of june 2018. Since then my bill from them has been sent to me every month showing that im in arrears for an amount close to R2000.00 for a contract and device i dont have, a case was logged on the 7th of july already still no feedback has been given