CELL C Worst Telecommunications Company ever

I had a contract with Cell C, I was on Debit order but Cell c decided not debit the account for the full outstanding amount at the end of the contract. The shortfall amount was handed over to CSS Solutions. I settled the account with CSS Solutions in October and provided Cellc with the paid up letter. Cell C has up until now not updated my information on the credit bureau and this has been blocking me to apply for any credit.