2012 GMC Terrain electrical system problems

Vehicle check engine light came on at 50,000 miles, would not pass inspection. Computer did not show what problem was. Car would cut off in drive in idle. Car would shake. Mechanics put in new parts and battery for more than $1200. Still was not fixed. Mechanic went to a dealership to inquire if they had seen this problem. At the dealership it was discovered that many of the parts that would cause the problem were on recall. GM had not posted these recalls or notified me, the owner.

GMC refuses to help. I am contacting because I own a 2012 GMC terrain and we just started having issues with out radio where it will turn on even with the car off. Our GMC dealer said that they have seen this issue alot and since my vehicle just came out of warranty in feb. It will cost us $150. What can we do since this is a fault in the radio flashing not something we have done. If the radio turns on while the car is off what else will start doing that.