Cell c bad service

Hello i am contacting you on this platform as the last resort as i have exhausted all others with no assistance i have been a loyal customer to cellc for years but today im being treated unfairly i had a contract and when it was about to expire i sent a email to collection queries and called customer care numerous times that i am canceling they continued to bill me and after 2months i reversed the debits my sim is blocked and now im told i am owing have not had a sim i lost job opportunities due to this i am not happy at all please resolve