Continued charges after cancellation of contract

Telkom billing - I have been trying to resolve an issue since the 30th of September 2019. I called Telkom to cancel my contract and was advised to give one months notice and do it online. This I did, and received an email AND sms confirming the cancellation. They continued to bill me for 4 months after this despite my monthly calls and emails querying the debit order deduction from my account. I then cancelled the debit order and reversed the payments as I had proof of contract cancellation (which meant that the money was deducted from my account unauthorised). I notified telkom of this. After this, they then refunded me and charged me over R200 per transaction for unpaid charges as I had reversed the charges.