Telkom still debits cancelled accounts

I have cancelled 2 contracts with Telkom through various channels, yet they still debit my account. the channels I used: Online (received confirmation emails); in-store (received reference numbers); by phone 3 times! (received reference numbers); by email twice! I keep on reversing the debit orders, but it is seriously costing me money now. I started this process on the 23rd April 2018 already, but they keep on debiting my account. What more can I do???!!!