Concrete piers are sometimes cheaper initially than steel driven piers, but the inability to drive to the depths needed to reach bedrock or load bearing strata creates the necessity for frequent post installation adjustments. Rooted in the expanding and contracting soil that initially caused the problem, problems are likely to continue. The strength of the concrete pile is limited to the strength and alignment of the pier sections. It's only as strong as the weakest link.
In areas of constantly wet soil (either from poor soil conditions or poor drainage due to improper grading), concrete piers will continue to settle in the soft soil or clay. Many of these companies offer soil injections to help alleviate the problem, usually requiring service contracts for repeated treatments which significantly adds to the inconvenience and overall cost of the repair.
PermaJack foundation repairs are unaffected by such conditions since it supports the foundation with a pier driven to bedrock or equal load bearing strata which makes the repair reliable and permanent.