Telkom pathetic customer service

During the beginning of June’20 we got unlimited data contract for our house. After a month we contacted Telkom regarding connection issues. We were notified we could cancel the contract for free since it was an issue with the towers needling upgrade, but this would take up to 6months. Case reference ***1. We took the option to cancel and on 25 August our device was collected by the couriers with the sim. Up to this day and with numerous emails and follow up calls, we still receive an invoice and every month they attempt to collect the money from our account for a service not being used and a device in their possession. Worse is we get an email to have our names blacklisted or reported due to non-payment on our side! Which is absolutely ridiculous for a billing system on their side which is clearly not communicating with the retentions/contract department.