VERY VERY POOR SERVICE WHEN CANCELLING A SERVICE

I cancelled my account in April 2018 because my line was down for a long time and FINALLY they told me cables were ****** and they won't be putting n new cables .. (WONDERFUL.. AND THEY DON'T INFORM THEIR CUSTOMERS... only those who complain.). So by August 2018 had FINALLY paid all that was owing. even got a ZERO account from them and no more bills until 2019... In April 2019 I got an invoice for R-214.66 Which I ignored... obviously they made a mistake. In 2020 April I got ANOTHER invoice. this time for 341.04. Now in 2021 August they are suing me for this outstanding amount. Sent ALL the necessary documentation. invoices and proof of payment to them AND THE LAWYERS AND DEBT COLLECTORS... but NO ONE READS the emails. And STILL THEY ARE SUING me for that strange figure PLUS interest etc. Talking to them is a waste of time. they keep asking for documentation and give me ANOTHER reference number to use.