The CC Departments of the Local Authorities had no idea what they were doing (although this could just have been a couple of them in Northamptonshire). So properly training staff and ensuring that the computer systems are up to the job would be a start.
I'm sure the stories of incompetence across the country are manifold.
As to calculating the actual £££ cost to each individual, I'm not sure how to achieve that on a fair and affordable basis.....