I am in a similar jam, and am looking at replacing some foundation wall to raise part of the house.
One of the SNAFU's I am running into is the engineers and contractors I've talked to so far all seem to be scoundrels. I've gotten wildly varied quotes, and several overt threats to call the county building inspector to come over and hassle me if I don't hire them.
I don't cotton to threats, and I haven't met a contractor among the rest that I would trust to work on my house. So it looks like I am doing this myself.
I have (and recommend you do as well) pulled the pertinent sections of my states building code before starting any work. Your local library should have it.
Not that it will keep people from messing with you. But it will at least make their job harder.