How do you correct a paid voucher that has been applied to wrong Purchase Order and Receipt?

We have a voucher that was applied to a wrong Purchase Order and Receipt. The voucher has been 3-way matched against the wrong PO and has been paid. Also, the payment has gone through auto-reconciliation. We would like to un-match the voucher against the wrong Purchase Order and Receipt and apply to the correct one. I had seen a prior case that is similar to this situation. The suggestion at that time was to cancel the check. However, because the payment is reconciled, we are not able to cancel. What are the steps to clear the purchase order and re-apply