Not sure why Telkom still exists

Got a Telkom landline installed in February 2018, which never worked and led to me cancelling it in March 2018 after numerous attempts to have it fixed. The struggle to have it cancelled lasted until April 2019 with Telkom still charging me for a cancelled product for more than a year. Eventually in May 2019 I got a letter out of them stating that I do not owe them any money, and that all products have been cancelled and incorrectly accrued debt erased. Fast forward to July 2020 and I get sent an invoice for April to June 2018. I try and phone them to find out what is going on, and after spending more than 30 minutes on hold, a lady answers and then cuts me off. I will actively discourage anyone from getting any product from them