Figure out what caused the crack in the first place, because if it's a tree root or bad ground, a new slab will just crack again too. Did the guy who did the patch say anything about the cause? I used Garcia Concrete last year for a small job and they showed up when they said they would, which is a miracle around here.
Bad ground" sounds a bit dramatic for a driveway crack. Most of the time it's just normal settling or weather changes. My parents' slab has had the same hairline crack for a decade and it hasn't gotten worse.