TELKOM - no feedback no help

The contract ended and we cancelled the mobile router contract 1000s of times, but never received any feedback. Telkom still deduct money and they keep on sending accounts. We stopped the debit order and reverse the payments, but then the next thing they handed us over for the outstanding amount. HOW CAN THIS BE RECTIFIED. the best of all, the Telkom mifi router never have coverage in the West Coast, so paid for something that never worked!