Telkom blacklisting

i cancelled some subscriptions on Telkom account via email in March. they kept on billing me, but i only paid for account i used. after numerous calls and visits to Telkom,to sort this out nothing was done. i then apply for credit elsewhere and find that Telkom have blacklisted me as a slow payer. THEY are the most useless bunch of people i have ever dealt with. i am looking for a number at Telkom to get this issue resolved.