The top-up history tab allows you to view the history of your top-up payment, with the specific data and time, transaction code, response status, whether it was approved or failed, amount credited, and the invoice for the payment. Only a top-up with a response status of Success will be credited to your account.
To view top-up history and invoice hover over the Configuration icon from the Navigation bar and click Billing. Top-up history and Invoice is the the the third item in the menu bar.
You can also view your invoice order by clicking on the eye icon located on the row of the order as shown below.
Clicking show receipt will display a 'printable version' option for your invoice