Before you get a foundation company to review and give you a quote, I highly recommend getting a structural engineer to review and evaluate your situation. You'll get an honest and unbiased engineering evaluation that may save you bunches of money. I know I did as 2 foundation companies gave me bids (15 peers from one and 22 piers from the another) at approximately $2,000/pier.
I was shocked and had an engineer assess my situation. Was the best $250 I've ever spent as he assessed my situation and immediately informed me that I had a slab leak and to get it checked/fixed. Sure enough, the drain to a tub in the center of the house disintegrated so all the tub water was draining under the slab causing the center of the house to heave upwards cracking sheetrock and jamming doors, etc.. After the slab leak,was fixed everything returned back to normal within a year later.
I've seen this several times since then with friends and family that ran into similar situations...