Telkom contract

I got a Router from Telkom but I discovered that there is no Telkom coverage in my area, so I phoned them and they advised me that I should cancel the contract within 7 days, so I did the cancelation but they keep on Deducting money on my bank account even though they collected they device, so every time I phone them to complain about the debit order they ask me to cancel my account everytime saying my account is not canceled yet. The money that I agreed to pay every month is R130, but when they deduct the money they deduct more. I don't know why they keep on deducting the money when I don't even have their device, in July they started deducting the money even though the I already canceled the contract, but what is worse now is that from August they started to deduct lot of money from my bank account, they deducted R330, in September they deducted R360, October R692, 14 November 2019 they deducted R821. So every time when they deduct the money I have to go to the bank to reverse the money, so today when I phoned them to complain about the debit order they said it's because my account is not canceled yet, but I canceled the contract 3 times already and they even said my account is in Areas, so I am worried now because I think they will put my name on credit beureur wheares I don't even own the device. Please help