Finance commission has been posted to a deal at point of sale and a receipt post to confirm that this money has been received. Deal has been closed.
If for any reason the finance company decide to claw-back the finance commission some time later it should be dealt with within the accounts side of the system. The deal should never be reopened to deal with this.
The reason being is that at the time the deal was closed you did receive this money. So all was correct and profit was correct. Money received has been allocated within the bank and reconciled.
Claw-backs are an expenses to the sales department as should be dealt with in the purchase leader as an invoice and coding it to finance commission to reduce it down this way.