Steering Is Tight problems of the 2011 Buick Regal

Our cur completely shut off all power lights engine everything doing 80 mph on interstate 84 in idaho. A semi seen it happen jumped in the middle of both lanes to block traffic so we could get to the shoulder. In a no cell phone area 13� we disconnected the battery and had to shift srive it in limp mode. No alert lights came on we took it yo a certified dealer to find the pistons, timing chain and other things are ntoken gm/ Buick was notified they decided to decline assistance because we are out of warranty 93k miles on the car and over 5,000$ in repair and possibly another 2100$ to repair the cadilitic converter. We were in a no cell service area and had to drive in the shoulder now the headlights won't turn on at all either. The car never alert us it just shut off the dealer says the oil was very low again no oil light came on with that yhe dealer says therecould be a bcm/ecm communication issue costing 1200. 00 to 2500. 00 to fix. They can't assess completely until the piston/ timing belt issue is fixed but the car is not communicating the steering is now super tight and the only yhing it says now is service stibilatrac and the mechanic didn't even bring that up.