Can Get Supersonic to stop billing after they stopped wireless internet in our area

During February 2021 Supersonic terminated WIRELESS SERVICE to us in Fairleads/Crystal Park, Benoni. This after weeks of problems / failures with providing wireless internet to us, always blaming "upstream" to be at fault (This if you could get to talk to customer service). They did offer "great" LTE as a replacement for their failed Wireless System. I DID NOT TAKE UP THAT OFFER. However billing continued even after relentless Emails to Cancel as well as telephone calls to them. Their excuse.......you are making spelling mistakes when typing our email address. It seems to be impossible to get them to stop billing, as not one email ever was returned undelivered. What a pathetic Company!!!!!