Hi,
I can't remember the name of the firm - something like terrateck or similar. They arrived in a 15 ton truck with a shipping container on the back, ran some high pressure hoses to the concrete slab, drilled some holes in the slab, set up a laser level, and forced an expanding foam under the slab till it was level.
$700 job minimum, then some extras.
Easiest way to get it done in my opinion.
cheers