How do we close a PO line when we have processed a credit to a voucher which has aleady been receive

hi community,

we do not have RTV's set up as our volume is low and we dont use inventory. We do tag our assets. We have purchased an item that came from a PO, it's been received, Assets are loaded in AM. We have been invoiced and the voucher has been created,  but we had match exceptions on price. The problem is in the meantime, we have returned the asset, and entered a credit voucher. The credit clears the accounting, but leaves the asset in AM and the PO still had the dollars open!

so do we need to set up RTV processing (for these small number of occurances) or is there another way to handle this?