Cell C inefficient

I had a contract with Cell which ended in 2019 but then I renewed it only for them to capture incorrect account to debit which eventually lead to account being handed over to attorneys Nimble and associates I made payment arrangements with them and got account paid up but Cell C have been failing to update my account status under Experain credit checks still showing as I owe them I have requested for paid up letter no success they keep telling me they are escalating to their legal department I don't have time am going to lose a home loan application due to this I need help