Will not cancel account and credit invoice - cannot contact them

On 30 November I followed the Telkom online instructions to send them an email with supporting documents to cancel my landline voice account effective from 31 December 2017. The only feedback I received was to say that my email was received. No feedback was given as to there being any issues with the cancellation or that the cancellation is approved even. I subsequently received an account in January with rental fees for the January-February period. After a long struggle I managed to get somebody to speak with, explained the situation and that I physically unplugged the telephone instruments on 1 January. I re-submitted my cancellation instruction to her expecting that the bill will be credited. I resubmitted my cancellation instruction and documentation to her on 18 January. Again I have not received any further feedback. Today (26 January) I received a sms reminding me to pay the outstanding amount so clearly nothing has been done about my query and again I cannot get hold of Telkom at all. In the first instance it is almost impossible to contact Telkom and in the 2nd instance they do nothing when you do get hold of them. I need Telkom to credit the amount.