HMRC Record of CIS Deductions

I regularly have problems with HMRC in respect of clients who are sub contractors in the construction industry. My clients provide records of the CIS they have suffered, but very often it does not agree to the figures HMRC have gathered from the Contractors monthly returns. On a number of occasions I have asked HMRc to provide an analysis of the figures they have on their system in an attempt to reconcile it to my clients records and identify where the problems lie.

HMRC's response is almost always no. They will not supply the figures.

I was once told by a disgruntled HMRC employee that they have the records readily available but have been instructed by their managers that they have to refuse to discclose the information as they do not have the resources.

Does anyone know if HMRC are legally obliged to provide this information.