After Carry forward Purchase Order Budgetary Control Balances requisitions converted to PO

Summary:

We have several Purchase Orders which have been converted from requisitions raised before the process 'Carry forward purchase order budgetary control balances' was run.

This means that when the invoices are matched there is no reduction in available budget for the current year, as in the current year budgetary control Expenditure is increased and Obligation is decreased.

We have instructed buyers not to do this. Is there a way to stop buyers doing this? How do i correct the current year budgetary control values? We do not wish to reduce budget to compensate for this, as we load budgets constantly - the issue is with Obligation.