Telkom is the worst

I have been getting the worst service from Telkom. Earlier in the year I took a contract for a router but when the router was delivered it was not a pocket router therefore I returned it and cancelled the contract within the stipulated time for cancellation and I was informed my contract was cancelled however I have been billed since then for a router I return and the billing is way more than what I would have paid on monthly basis if I did not cancel the contract I'm paying for a router that I'm not even using. I have been calling Telkom but they keep saying they will come back to me but never do. The last time they said the matter is handed over to their finance department but the debit orders still continue on my account. I would like assistance atleast from their head office then.