Exceptionally bad service

I sugned up for inter service in January 2023 for a trial period of 7 days as they offered me and paid the R499. I tried and tried but couldn't get a proper signal. I cancelled via email (the only email address that was available) and it came back undelivered. I tried to phone numerous times on the only number available but never could get through.in desperation, I reached out on their Facebook messenger. A person, Leshaedi La Bakone answered and said there was some sort of problem. I rep**** to tell her that I want to cancel as I can not get a signal and I am not interested. Because it was a trial period, they were supposed to pay back the amount that I paid . Instead I got an invoice a few months later tor another R499 and the in July this year a letter from a debt collector of R750. Now after another few months I get another reminder for a payment. I DO NOT HAVE AN ACCOUNT WITH THEM AND NEVER SIGNED A CONTRACT!!!!!! I don't even stay at that adress anymore! I still cannot find a number that I can dial to talk to someone, because it is only a voice with an automatic reply. HOW ON EARTH CAN I SORT THIS OUT FOR GOOD!!!!!!!!???????