Rear Suspension Springs problems of the 2013 Cadillac XTS

My 2013 Cadillac Xts4 premium rear suspension level system deflated while driving and didnt stay raised in the rear. I pulled over to see and the rear end was too low. I shut the car off and waited a few minutes. I started the car and it raised up until it reached height level. I then drove off and a few minutes later it happened again. When I stop and pull over and restart the car, the air compressor kicks in and raises the car to level and the air compressor shuts off once height level is achieved. I went to the dealer and was told many suspension problems with this particular model and I would need new struts, shocks, air springs, air ride compressor, and air lines. I'm out of warranty and I can't afford to pay for all of that. It was riding fine and the next day it just gave up. The suspension feels like a piece of junk and I need a new suspension for the Xts and I believe this should be resolved and paid for by gm. The car could've lost control and could've killed me and my passengers along with anyone around me in the freeway. It was riding fine and within seconds, the entire suspension failed. I want gm to fix my suspension because it failed after warranty expired.