A non-partisan government office said labor costs, not over-payments to pension funds, is at the heart of the budget problems at the U.S. Postal Services. The Government Accountability Office said, \"We have not found any evidence of error of these types,\" referring to over-payments that two independent audits, the Postal Service inspector general and the Postal Regulatory Commission all said had put the service in a huge hole, The Washington Post reported Thursday. Congressional Democrats have gone along with the argument and concluded that the postal services should be refunded $75 billion. But the GAO in Tuesday\'s report said that strategy would end up costing taxpayers $85 billion, which would be raised \"through tax revenue or borrowing.\" In addition, the sum \"would not be sufficient to repay all of USPS\'s debt and address current and future operating deficits,\" the report says. Rep. Darrell Issa, R-Calif., said the theory of $75 billion in over-payments was a ruse. \"It has simply been a disingenuous claim used to justify legislative proposals that would use billions of taxpayer dollars to cover up declining Postal Service revenues,\" he said.