Cancelation Not Achieved

I canceled a contract in Feb 2021 and confirmed this in March 2021. I was still being charged for it but I did not pay because I thought it was a system error. I got an email in September 2021 to tell me the contract had been canceled due to non payment but I must still pay for the account. Every time collections has contacted me, I have rep**** stating I canceled the account and I have never received a response. Cut to today when I check how badly my credit score has been altered, I call the center. All they have told me is that because whoever I dealt with in Feb and March didn't put the cancelation through, despite me confirming it had been canceled, I must now pay the arrears. I have not used anything on this account ever, I will not pay for a service I did not use on an account I have already canceled