After existing with a sloping, tilted front porch slab for over 10 years, I did some idle searching & stumbled onto the solution provided by TerraFirma. I read what they offered, then did a targeted search, as well as research into the alternative solutions available, now that I knew there was something out there to address my slab problem. TerraFirma's solution sounded to be the best available, so I requested an on-site visit. That was scheduled & we met as agreed. He reviewed the work to be done, then explained the process that would be followed to correct the problem, along with what to expect afterward. I was given an estimate, which I accepted. I was soon contacted by the office in Roseburg, to make an appointment, 2 or 3 months out, due to their heavy workload. When the time came, they showed up on schedule & got to work. Using a long hose from the truck & specialty tools designed specifically for the task, they made the necessary cylindrical holes at the locations determined to be optimal, then began the actual releveling process. It took about 4 hours, from start to finish, & the slab was back in position, with a guarantee that it would remain stable, within limits, for the length of the guarantee. I had prepared myself to follow up immediately to do the necessary cosmetic repairs to return the appearance back to what it was before the subsidence began, but was happily surprised to find that the only thing necessary was to replace some trim I'd found necessary to remove when the sinking began... less than an hour's work. As to the surface appearance of the slab, they had drilled far fewer holes than I expected & the appearance when they were done was such that they were barely visible & only nominally so, at that. Yes, I was very happy with the results.