Scales infestation – nothing is working and cinnamon plant is getting worse

Any advice on permanently getting rid of scales?

So far, I added bonide systemic houseplant insect control to the soil, and every week I’ve been wiping and spraying down all the leaves with a mix of neem oil, insecticidal soap, rubbing alcohol, and water – but the scales came back every time. And my cinnamon plant is only getting worse. I’m worried it might not make it. The lower leaves are drying out and falling off. And I’m noticing the tips of the upper leaves starting to dry out as well.

This is on of my favorite most unique plants and used to be one of my easiest plants to take care of but now it’s struggling bad. 🙁

FYI – I just wiped down this plant prior to taking this photo so the scales can’t be seen here. But they will likely return next week as they have been doing.

Any advice?