Trying to cancel for over two years

My contract was up for renewal - I did not renew and cancelled - telkom carried on trying to charge me for a service I had been trying to cancel - 22 cancellations sent to the e-mail address supp**** by the call center - there is no other way to cancel. I had to block Telkoms debit orders as they are just to stupid to acknowledge and action a cancellation. Over two years down the line, they are now listing me with a default against my credit score. This is grounds for legal action! *********** is not good enough to describe these clowns