Account paid up: No update at Transunion & No paid uo letter

I had an account with cell c whch went on default b z I couldnt pay, I then settled the account this year march 2022. I requested a paid up letter via email whch Cell C did not send. The full balance has been paid but no update at Transunion, it still shows as default.

Cell c has dented my credit rating, I have sent several emails to them wth no luck.. they dnt respond, I called them but still They kept on sending me through to other departments.

Cell C has the worst customer service Ive ever came accross, once they take ur money they dnt care.