I appreciate all the efforts you've exhausted just to get this working, aseque.

To find an application that allows you to integrate with QuickBooks Online (QBO) for electronic invoicing, I recommend exploring our App Center. 

Here's how:

1. Go to Apps, then click Find Apps.
2. Use the search bar to look for an app.
3. You can consider entering words such as "E-invoicing."
4. Choose an app that best fits your needs and click Get app now.

I'll be right here to keep supporting you throughout this process. If you have any other questions related to invoices or any aspect of the program, feel free to ask.