Foundation Repair is a specialty service. There are many handyman services, pest management services, etc. that could offer what seem to be competent solutions and products, however are often not Engineer certified. Some things to put on your guide:
1 - At least a Class B Contractor. This means they make more than a specific amount in gross receipts. Class A can be a higher amount, so that it means they're a more substantial company. This doesn't mean they are necessarily much better than the usual Class B... larger ways they got more income from customers, and perhaps not in the region in which you're concerned (foundation repairs). Also, concrete corrosion engineer might not exactly provide you the individual service you desire, or has independent estimators that are not really attached well to the company (any might not exactly communicate well about your job!).
2 - Structural Engineer Certified products and installation. Your home's foundation is a vital section of the value and operation in your home. Any solutions for repairs need to take into account many engineering factors, for example typical load, footing configurations, etc.
3 - Masonry work. If your property is wood frame and siding, ignore this place. If you have any brick or block, chances are there'll must be repairs, tuck-pointing, brick replacement etc. done after the foundation continues to be repaired. Your foundation could possibly be stable now, but it might still look bad, with big cracks running down the wall!
4 - Warranty. Most foundation contractors provide warranties, in which have transferable, life-of-structure warranties.