Cell C Contract ****

I had an existing account with cell c. In 2020 when i lost my job, i called in and spoke to a consultant explaining my situation and asked for my contract to be canceled and a settlement amount. I settled the account.

Fast forward to July 2022, i received a call from a debt collector informing me of my outstanding balance of R7800. In attempt to resolve this, i was given a case number and nothing was resolved.

Please assist with this as it is affecting my credit rating.