Vodacom keeps invoicing me for handset installment when contract has ended already

Cellphone contract ended but Vodacom still invoice me for handset installment. Have been calling since the 8th of March to get them to fix the invoice and avoid debiting my bank account wrongly. Made several calls to customers care and even send emails and no one calls me back or make sure that the issue gets resolved. Worst customer care experience ever. They don’t care or are even able to help customers to fix THEIR mistakes. Once they have your bank account number they will simple just debit any amount.