2 years since I have closed my Rage account and it still shows on my credit profile that I am in arrears!!!!!!!!!!!

I use to be a regular customer with Rage until I lost my job. Of course with be being jobless I was not able to stay up to date with my credit repayment instalments. Eventually I started working and cleared my balance owed to them and closed the account. I received my paid up letter and was advised it could take a 6 months to update my credit profile. It has been 2 whole years since then and my credit profile still shows that I owe Rage!!!!!!!!!!!!!!!!!!!!!!!!!! This has sabotaged so many credit applications especially with trying to apply for a home loan! How do i take this further? My credit rating and profile has been sabotaged by someone In Rage not doing their job properly!!!!!!!!!!!!!!!!!!!!!!