Don't sign a contract with supersonic as apparently it's impossible to cancel and you will keep getting billed.

I opted for a lte wifi contract around april 2020, which I cancelled 3 September 2020 because of the slow internet speeds and poor service. I paid for September as it served as my notice period. I sent back the router in October and even phoned to ensure everything is done. Yet I still got billed for October and November. It still says my account is active and that I owe Supersonic over R2000!! I can't get through on the customer service line as I am usually caller number 30+, and no response via email. This is ridiculous. Please stop *****ing my money. Definitely the worst ISP I have ever been with.