Foundation Separation

Hello. We are having some issues with our pourd concrete foundation. Our house has a concrete slab porch (about 5ft by 24ft) on the front that comes out at the top of the front foundation wall. about 2 years ago the front of porch dropped about an inch. This caused the foudation to crack right in the corner where the side and front foundation meet. At the top the crack was about an inch wide and tappers down to the floor of the basement were it is a couple milimeteres. Porch sank because the downspout went into the ground right beside it. We rerounted the down spout away from the house and had the foundation injected to seal the leak. The intereior walls were left for a year to see if it would leak then I spray foamed to fiish the basement again.Now a year later it's leaking again. We've had a couple companies come in and they seem to be going about things a little differently.
All of them want to dig up the exterior and around the porch, then under pin to stablize the pourch. After that they differ. One want to only fill the crack with concrete grout then water proof the wall and backfill. The other want to reiforce the wall by bolting flat steel bars wrapping around the corner as well as filling the cack and waterproofing.
The last company wants to cut the corner out about a foot on each wall,then using rebar to to tie into each and repour the corner, followed by waterproofing and then back fill.
The first 2 companies are pretty close in price at between 13-15 thousand. The last company wants just under 20.
I've pretty much rulled out the fist company as i think the walls need some kind of reinforcing. My question is, is bolting steel plates around the corner enough or does the corner need to be replaced?

The way that foundations are built today is, you dig a hole about five feet bigger than the house, when it is back filled it is seldom compacted and often sinks over time.
As a way to combat that people tie sidewalks and poarches to the foundation.
I think that had more to do with this problem than your downspout. That's just my opinion any way. With your first patch job leaving things in place, there continues to be stress on the wall and sooner or later you will have another crack toward the other
end of the poarch. Mud jacking the poarch should push the wall back into place but the crap that has found itself inside the crack will make that a problem.
If there is rebar in the wall, it has now been damaged with water and air and will have started to rust causing more damage to the concrete near the crack.
So I would go with the guy that wants to remove some on both sides. I would add rebar to tie new to old but I would also require that after it has been smashed out I would use a diamond blade to make a nice clean cut on the outside so a gasket can be added. I have only used it one time , when poring a foundation in two peices we stuck this stuff to the face of the first one to seal it agains water. Black foam, peel and stick 1/4"x 1".
When mudjacking the poach, do spots for the whole twenty feet to make sure this isn't an ongoing problem.