I have been researching via the ICOs office for a similar issue with Nationwide. The credit reference agencies are wrong to tell you they have no power to update the records.
This is what the ICOS guidance on the matter says (point 41)
Credit reference agencies potentially have a defence against action through the courts by individuals who successfully challenge the accuracy of data received from a lender. However, this defence is only available if the agency takes reasonable steps to make sure the data is accurate and, as soon as they become aware of the challenge, takes steps to mark the file accordingly. Records where the accuracy is challenged can be marked as ‘under query’. This marker alone is unlikely to be sufficient to provide protection against claims, including those for compensation. Agencies should therefore ask the lender to
substantiate the disputed information within a reasonable time frame, for example, 28 days, and, if the lender is unable to substantiate the disputed information in that time, should suppress the information from the file.
Quite clear really the CRAs cant just brush you off with "its not our problem"
Full file is at
http://www.ico.gov.uk/upload/documents/ ... %20doc.pdf