Hello there, @Sim_D.

At this time, there isn't a specific report that shows the original amount of the PO, the billed, unbilled amount, and it's actual paid status in QuickBooks Desktop. However, I've got a workaround that you can try to gather the said information that you need.

You can pull up two separate reports, which are the Purchase by Vendor Detail to see the billed transaction of your vendor and the Open Puchase Orders Detail to see the balance and amount of the PO. To access these reports, you can go to the Reports tab and tick on Purchases, then choose any of the said reports: 

After that, you can export these reports to an Excel file and customize it according to the information that you need to create a single report. To help you with customizing them, you can utilize this reference for more details on what are the details that you can add to the report: Customize vendor reports.

Know that our developers are always finding ways to cope with your business needs. I'd encourage you to visit our Firm of the Future site to be updated with our product road-maps.

Let me know if you have any other questions. I'll  be right here to assist you further. Take care!