Still one of the most recommended products to use for scale control is a horticultural oil of some sort. They make some that can be used even in the heat. I think that a summer weight refined oil might even be better than neem when it comes to scale control.

The immature stage of scale insects, called crawlers, are very hard to see and most people wouldn't even recognize them if they did see them. Those get missed when one goes after the adults with alcohol and a swap or toothbrush. Perhaps you might consider misting your plant with alcohol after you've removed the adults. A solution consisting of one part alcohol to three parts water is usually sufficient to get the job done.