Need to update invoice control amount. Is there API for invoice update?

Is their an API in Oracle r12.1.3 to update ap.ap_invoices_all.control_amount? 

We upgraded to R12 back in October 2012 and are still struggling thru payables approval and how it works with ebtax and sabrix (3rd party tax partner).

We need to update 1796 invoices (nbr today.. who knows tomorrow..argh)  that are on line variance holds due to payables approval job created a tax line resulting in the total of the invoice line amounts to be out of  balance with the entered invoice amount.  This seems to be resolved by setting tax control amount to 0.  Doing that results in the payables approval job to remove the previously generated tax line.