When a bill is saved or approved in Xero, it locks the purchase order in Factory so that it can no longer be changed or archived. The accounts person might have corrected prices in Xero etc, but the staff member in Factory might not have had time to update this in Factory yet and can no longer change anything. We have then tried voiding the Bill in Xero but it is still locked and now we do not have the bill in Xero either. We need to be able to unlink the bill in Factory, so that it can be updated and sent through to Xero again.