Ignored cancellation request

Due to a deterioration in the ADSL service in my area, which Telkom is apparently not willing or able to address, I decided to cancel my Telkom landline earlier this year. I did not need a landline for telephone calls only internet access, which I now have via a local wireless provider. I first submitted my Telkom landline cancellation request by email on 23 May 2017 (with automated receipt confirmation), and again, but my request was ignored until I cancelled my debit order via my bank. On 11 August 2017 I received a text message from Telkom saying that my cancellation request was backdated to the initial request date and account adjustments were done. However, on 16 October 2017 I received another text message from Telkom saying that my account ********** 90001 is in arrears of R725.72 and I should make a payment immediately and contact Bongani on ********** 595 to prevent further action being taken. I have not received anything to this effect via email (my email address has changed due to a change in ISP but I have updated it on their website) or been given an email address to contact. I am not prepared to pay another cent or waste my time and money calling anyone to sort out the mess caused by Telkom's sheer incompetence. I would never use Telkom again as they cannot be trusted to uphold their contract terms of processing a cancellation request.