I know personally of four schools in two separate LAs where funding was top sliced, so I would imagine it would be true for other schools in the same BSF wave in those LAs. There is nothing sinister, illegal or immoral in this, the LA must choose if it is to use its grant funding from central government (and local council taxpayers) to pay for these sort of services, or use money from central government provided by the BSF program. I suppose a wealthy LA could use reserves to cover these costs & pass on all of the ICT funding to schools, but this did not happen at the schools I know of.
I was Chair of Governors at one of these schools so I had every opportunity to see the 'numbers'. As Governors, we were given a stark choice, accept BSF ICT funding and have a managed service, or do without the managed service and say goodbye to the money. The Head Teacher & I discussed the choice at length, in the end we decided we could not turn down the investment, we owed it to the children and staff at the school to provide the best resources we could.