Finally my MP writes back about the CSA

I think that if they do decide that it aint worth chasing them due to costs etc, they should compensate the pwcs with the amount owed to them for non collection. This would only apply to those cases who already have arrears owed. They could write off the amount owed to the state as they have already paid it anyway, so it would not be cost effective to continue to chase these cases where the nrp isn't paying but it would be highly unfair if private pwcs whose nrps have racked up large arrears should have to go without. Win for pwc, win for nrp, lose to the taxpayer, who wouldn't notice it on a weekly basis anyway AND it would only be a one off.