Most organisations do not have a Power BI problem. They have a modelling problem that Power BI made visible. When four reports answer the same question four different ways, the fault is almost never the visual layer. It is that each report carries its own copy of the business logic, built by whoever happened to need it first.
We build the layer underneath: a dimensional semantic model with one definition per measure, tested DAX, row-level security that matches how your organisation actually delegates authority, and a deployment path from development to production that does not involve emailing a PBIX file. Reports then become cheap, because the hard thinking already happened once.
We work at whatever altitude you need, reviewing an estate someone else built, taking a first model from zero, or embedding with an internal team that wants to own it afterwards. We write the documentation on the way through, not as a closing invoice item.