Last year, we learned that our government was starving the Ombudsmen's Office, leaving it unable to perform its basic functions (while the resulting media attention has seen a budget increase, its too small, and very explicitly won't see the Ombudsmen's investigators getting the pay they deserve). We're not the only ones: the same thing is happening in the UK as well:
The [Information] Commissioner stressed in frank terms the financial difficulties his office was facing. At the moment, the ICO is funded by the notification fees that it receives under the Data Protection Act and grant-in-aid that it receives from the Ministry of Justice. The former brings in substantial amounts but is ring-fenced – it can only spend that money on its data protection-related activities. FOI activities are entirely dependent on MoJ funding. That funding has been progressively reduced over the last few years. The Commissioner stated that:
"If grant in aid was cut further, action on anything other than routine freedom of information enquiries would be impossible."
This seems to be a common tactic of governments fearful of the greater transparency and accountability that freedom of information brings: rolling back the law would be too overt, so they just make it meaningless in practice by underfunding the oversight body, or imposing high fees for its use. The net result is that no-one can effectively challenge the government's decisions, and they can withhold what they want.
As for how to stop it, empowering oversight bodies to charge investigation costs to the agencies being investigated would seem to be an obvious solution.