To view outstanding invoices, log in to ComPay — or, if you're already logged in, choose 'Outstanding Invoices' under the Invoices link. You'll land on a page like the one below.
You will notice that there is an option to search for specific payable invoices by date, Payee and Payer.
To see more detail about the invoice listed, go to the 'View' link at the right end of the column. You'll be taken to a detailed summary of the invoice, which contains the Invoice Details, Invoice Header, Invoice Line Items, Associated Payments and options for going 'Back', 'Pay' and 'Print'.