Keith writes:

So now I'm stuck with these invincible fleas. Does anyone know of any
alternative methods I should try?

Find something you can apply yourself that is effective. Not just
permethrins. And then violate federal law by multiplying the dose. The
recommended doses on consumer products tend to be minimal, as are the
"professional" products and trade, these days.

I don't know what "bug bombs" you tried, but the Raid fumigators in the
little blue cans are quite effective, and you can multiply those, too.