Vodacom are undercover ******

I have been using a contract router from Vodacom with data bundles given to me monthly. Their contract came to expiry on 26th of February 2019, to ensure the account is closed I made a call to cancel the contract and the consultant ensured it was closed. On month end there was no debit order but I received the data and the invoice, I called them to understand what was happening, my calls were transferred from one department to another and I ended up not getting any help. No I received an invoice of bill and the amount that has interest to account that I don't even use, I still get transferred to all the department like I'm asking for donation. Which makes me believe its their way of *****ing people money, I have been loyal to vodacom for so many years, now they broke that loyalty for wanting to make me a bad person on credit bureau