CellC Fibre cancelation troubles.

I cancele my fibre account with CellC in May 2021, dis a credit check an saw they did not canceled it and that I owe them money for not paying. Didn't get debited or anything. They kept on adding the money every month with emailing ot phoning me. When I phone them to cancel, they say I have to email to cancel. Emailed 3 different email addresses and yet no response. Even the email on the statement is wrong, according to the call centre. Worse service ever. No email back or phone calls stating that I wasn't canceled and that they are adding the costs. The mbps also somehow increased and the monthly amount, without my knowledge or an email notification.