To look at your past payments, once you log in to the portal, click the Accounts tab on the top right menu next to the Logout link. You will see a calendar appear with the first of each month shown in a color and a drop down for the year as well. If you click on the first of the month which is your bill cycle date, you will see a line appear at the bottom of the calendar showing the invoice in a HTML format along with the amount of the invoice. Click on the HTML format (in the Invoice column) and then you will see the invoice with a notation at the top on whether the payment was successful or not. You can also see other information about that payment notated around the page.