Disenchanted with my VolvoS80

Purchased a used 2000 S80Volvo with 70K from an individual in April. Since then, I replaced the front and back brakes because I received a message for ABS Service Required code along with a STC code. The codes continued to appear after I had the brakes replaced. I suspected that since I hadn't replaced the brakes at a "Volvo Dealership" that they were not able to turn off the codes. Unfortunately, the nearest dealership is 70 miles away. A few weeks later, my car died as I was driving down the highway at about 50 mph. I happened to be in front of an Autozone but nothing they could do, it's a Volvo and parts would have to be ordered. I had it towed. The mechanic said it was the Mass Air Flow Sensor. He replaced it. Days later I had a different mechanic who worked only on foreign cars say that the alternator needed to be replaced at the tune of $674. including parts and labor. About a week after that, I took it to a Volvo Dealership because of an Emission System Service Required Code had appeared. The dealership hooked it up their machine and it said that I was in need of a MFI module 8619545-0 Code ABS 0070 and Replaced ABS Control Module at the tune of $944.89. Now after ALL of that money spent, one would think the problems would cease! The dealership also said that the Mass Air Flow Sensor must be faulty and would need to be replaced. I checked with my hometown mechanic and he said he would replace it for me BUT that he had done some research online and said that it was sounding like I would need to replace the throttle body??? That it could be causing the Mass Air Flow Sensor damage. ??? He also stated that you can't order that part. ???? Why not??? I'm confused. Am I too trusting?? Or is this the reality of having a volvo???