Okay, it sounds like the exhaust system rotted out and needed replacing. As I suspected, he never changed the oxygen sensor. I’m wondering of he checked it.
The “maintenance required” light may be the one that tells you it’s time for the periodic maintenance. Look in your owners’ manual to see if that’s the light you’re seeing. The Check Engine light is a different one, and that’s the one that indicates a problem. But, again, check your owner’s manual I can’t tell for sure which one is lite from here.
I gave your problem a bit more thought and realized that ither possible causes exist than what I suggested that could cause severe shaking at idle, including transmission problems. But The engine mounts were clearly not the cause of the problem, the problem clearly hasn’t been properly diagnosed yet, and you clearly need a better shop.