Vodacom definition of cancelling contract does not include the WORD device

My daughter received a call from Vodacom to upgrade her contract. She paid the full amount outstanding on the old contract after receiving a quote from the call centre to cancel the contract and to only be debited for the new contract. Now they are debiting her new contract account with additional amount monthly since January 2019 stating that the device was not cancelled. Surely if you settle or cancel the old contract it includes the device which they are stating was not requested by her to be cancelled. Surely they are *******ly debiting her bank account for an amount they do not have authority for.