To remediate a situation my concrete company caused by changing the layout without consulting me, they propose to add a ramp partially on an existing (though new ~10 days) slab. I'm worried that it won't be durable, and I am having trouble trusting them for obvious reasons.
Here is a (bad) drawing of the proposed ramp: 
It would be straight on the left matching the lower pad, I'm just bad at Photoshop. The ramp will be 2 feet by 8-10, and will rise to 6 inches high to meet the higher level.
They say "We will cut and remove the lower portion out of the trash can pad so we can pour solid 4" down so we are not going to zero on top of the existing. The area on the sides will have rebar to tie the two together. This is standard practice."
Is that OK, or should I insist on tearing out the lower slab and redoing it with the ramp as part of the same pour?
Background:
I had a company build a concrete pad in my back yard. Without consulting me, they changed the layout to have two levels: a lower level for a small extension for my trash bins to sit on, and the main part 6 inches higher.
I wanted the whole thing to be the same level as the lower pad. They obviously don't want to tear it all out and redo. I'm mostly OK with the higher level, except the trip hazard, since my young kids will be playing back there.
Best Answer
They are taking out the lower area to have a full 4” pour, they are tying them together with rebar so I don’t see any issues, for foot traffic in a small area 2” even works. I see driveways poured at 4” all the time so I think they are planning a proper fix as long as you are happy with there design.