I have copied the following from an article in the Telegraph, it may help.
No one regulator takes responsibility for credit file issues. On the one hand, if the problem is materially unfair, the wronged person could complain to the Financial Ombudsman Service, which says it receives "hundreds" of complaints a year about credit file problems.
The Information Commissioner, which deals with data protection issues, can also get involved. It received 140 cases related to inaccurate information held by credit reference agencies last year, and 536 about lenders putting inaccurate information onto files.
Frustrated victims could also try the Credit Services Association, the trade association that represents debt recovery agencies such as Wescot. However, a spokesman said that while those who were struggling with debt and ensuing credit file problems were well served by debt collectors working with organisations such as the Consumer Credit Counselling Service (CCCS), those who had simply been wrongly named as debtors did sometimes "fall between two stools".