Most calls start with something you can see. A floor rolls toward one corner, a door won't latch or a crack runs up from a window. Once a floor tilts more than about 1 percent, most people notice it just walking across the room. Those signs tell you the foundation moved. They don't tell you why, and the why decides whether a lift holds.
The price depends mostly on what your house sits on and how many piers it takes. A slab costs more to raise than a pier-and-beam house, for reasons I explain below, and every added pier means more digging and more time. The schedule turns on the same things, plus any drainage or footing work the cause calls for. Your written estimate puts each of those on its own line, so you see your number before we start.