So if the house was built like we build them it goes something like this.
Dig down to solid soil that can support the house and pour a footing, something like 18" wide and 8" deep, on top of that pour a foundation to height and backfill that with compacted sand and pour the floor level with the foundation.
You said this problem was about 9ft in each direction from the corner, my guess is that the foundation is broke in two places and tilted down to the corner. If your guy lifted the corner up he lifted that hole area off the ground including the floor.
So if each crack is 9 ft away from the corner he lifted 16ft of footing which is 192"x 18" =3456 sq inches all being supported in three places, maybe 1/4 of the weight is resting on the dirt right at the crack on each side. One half of the weight is resting on the pier, so he repalced 1700 sq inches of footing with 300 sq. inches of peir.
If the floor was also lifted at that time, it was also lifted off the fill and that weight was added to the problem.
If what he did worked at the time, the rest of the footing should have underpinned to actually solve the problem.
Under pinning would have been to dig under the footing and put larger chunks of poured concrete to spread the load over a larger area and fill the voids and the floor should have been lifted with a foam fill at the same time.
My fear is that the footing has settled at the cracks, if not you may be able to jack it up again and underpin the footings, if the footings have settled at the cracks, you have a much bigger problem.
I hope this helps you to understand what is going on and I think you should find at least 4 foundation pros in your area. If they all have different solutions, get an engineer to design the fix. This is not usually diy freindly.