So, you complained because they should have but didn't get your prior approval and thus you paid NOTHING? Sounds like they then admitted their mistake and handled it at their expense, their loss but why are you then complaining? It's possible that they're a legit group of people and that maybe a new or temporary service writer who was ignorant botched your situation w/o evil intent. We get that too, an experienced writer goes on vacation or is sick, etc so they move another guy from another dealership in to help out BUT the guy knows nothing about Volvo and thus makes a few costly mistakes. This can happen anywhere.

As for Lexus, they might be lower maintenance at first BUT I've heard that if you keep it to 60K miles, the cost of a 60K service is so high that many sell the car at that point. That's rumored to be their plan, then they get you into another new Lexus and resell your old one.
There is no perfect car and all newer cars require dealership diagnostics, software, etc. Our federal emisions had made all that a reality.