Telkom are *******

I had a cellphone contract with Telkom which ended last year in September ever since I took the contract I was honoring it by paying, I went to their offices at Shelly Centre and I made it clear that I will not be renewing my contract with them when it ends and I don't want their data. It was cancelled but now they keep on debiting my account and I'm forced to reverse the funds they debit, this have a bad effect on my credit score.