How can I level a slab with floor drains?
When you have floor drains, the installer should have established a fairly smooth slope toward those drains into the floor as part of the process of "floating" (levelling and smoothing) the surface of the concrete. This is slightly annoying but not difficult -- I've done it for summer-camp shower houses, as a mostly-untrained volunteer -- so a pro should have been able to handle it. If it's really their error (rather than someone tromping around in the wet cement after they levelled it but before it hardened), I agree with @MichaelKaras that it's their responsibility to figure out how to fix it.