During a review of payments to supplier invoices, the internal auditor identified that the IT...

The alert is a control that should never be ignored, and suppliers should be advised that invoices will not be paid unless the invoice is equal to or less than purchase order value

The manager should raise a purchase order amendment each time the amounts differ, and the supplier should be asked to quote the amended order number in the invoice

The manager should establish a monetary limit on the amount of difference that will be tolerated, where the IT process will allow the staff to ignore the alert

No additional controls are needed, as it is appropriate for a process to allow staff to exercise discretion when processing invoices