paying for no service

I initially app**** for supersonic fiber but the service i received was not on par with other isp's i sent them a mail before the fiber was activated i got no response i went to a rival isp and they gave me exceptional service i was active immediately. I continued receiving statements from supersonic for R0 for a year then all of a sudden i have been billed R300 + after a year for a service I am not using i have been receiving threating calls saying i owe money when I don't. getting through to supersonic is impossible the drop calls and cut WhatsApp chats that's why I am in this mess. its not a contract as stated so why do I owe money???? 0 stars