Dealing with Housing Benefit Rent Recovery

I've recently taken on a landlord who has a lot of tenants on housing benefit and a number of these have recovery's against their claim.

I've run the council to try and get more information on the claims but they aren't willing to let me know any further information due to data protection.

What i'm looking to find out if anyone can help me is how to best approach tenants about them paying the recovery and what success they have had in the past.