Understand impact of Invoice Variance

Summary:

We have a PO created with Incorrect Line Amount ended Fully received, Invoiced and accounted. The Line was meant to be for as qunatity 4.95 and £1 as price due to existing configurations. Requisitioner entered £4.95 as price and 4.95 as quantity which equated to £29.4 including taxes. This was fully received. When Invoiced the invoice stated 1 as quantity and £4.95 as price. Now PO sits with ordered £50.50, Received £50.50, Delivered £50.50 but invoiced £30.95. We are unable to change the PO- to reduce the quanity as it is already matched to invoice which is now fully paid