Blacklisted for an account i paid years ago

I had an account with RCS in 2007, it was paid years ago, they now have me listed on Experian as an account in arrears, and current, this negatively impacts on my credit score, and has caused me to lose job opportunities. I cannot believe they are so negligent, I have made 3 requests to assist with the updating of info with Experian but RCS refuses to assist, they dont even get back to me. THESE COMPANIES DO NOT REALISE WHAT THE IMPACT OF THEIR NEGLIGENCE HAS ON PEOPLE'S LIVES.