Sounds like they replaced the SMC, PCV and the pads etc. But I don't hear any mention of checking, cleaning or replacing the front pads. If the front pads are dirty or sticking, it can also cause the rear to drag. There have been so many recent cases of incorrect brake bleeding done by various shops & folks, I'm wondering if your system was bled correctly, using the OEM service manual procedure, or if someone attempted to use shortcuts in bleeding. This would also cause alot of your problems. I'd ask the mechanic or service manager how the brakes were bled. Alot of the shops don't follow the service manual's procedure, as it takes too much time, its a pain to remove all the plastic, ties up our mechanics too long, etc. I'd start by removing ALL the pads, cleaning all the pistons, lubing all the pins, and making sure there is no scaring on the pin causing it to bind, then Flush and Bleed the entire system using a motion pro bleed tool. They probably used a mity vac type bleeder and there is probably still air in your system as well.
Good luck.