Trax problems

I bought our Trax in 2015 used from a GM dealer about 125 miles away from our home, it had about 17,000 miles on it. In 2016 we started having rear brake issues and took it to a local GM dealer it was covered under warrant but it went back 3 times . Then in 2017 it had a couple recalls that the local dealer. Also in 2017 the motor went to Knocking hard. The local dealer said the valve cover was loose and scheduled an appointment. surprise came when they found the plugs were almost out of the block and the coil packs were holding them in, It had about 30,000 miles on it. At 45,000 we changed the tires before winter at about 50,000 miles the turbo started leaking coolant the local dealer said it was not covered under warranty and GM would not replace it. They wanted $1700 to replace it . That is my rant now how do I put a new turbo that is OME that cost $280 on ?