Listed on ITC - yet account is up to date

My account is paid by debit order every month and it is up to date . RCS has listed me on ITC and put a default against my name for the account . I have tried calling to get them to send an update to remove the listing but I have had no success . I spoke to a team leader who said she would call to give me an update and reference number. Its been two days and I am still waiting for the call. The listing has dropped my credit score considerably. RCS has no sense of urgency and I have not received any apology for this mess they have created. Instead they sent me a paid up letter - I dont want a paid up letter I want them to instruct that the listing be removed !!!!!!!!