Telkom refuses to cancel my account

I followed the Telkom instructions and submitted my landline service cancellation on 30 November to take effect from 1 January 2018. On 1 Jan 2018 I unplugged my telephone instruments. Then I still received accounts from Telkom and the service was never cancelled by Telkom. I have called Telkom several times and each time had to resubmit my service cancellation documentation. Never receiving any feedback. I thought the last time that definitely now the service is cancelled and the incorrect account is reversed/credited and today I received yet another account now with another month worth of rental added. Can Telkom please cancel this account and credit all fees charged after 31 December 2017.