2019 Cadillac XT5 STEERING,ENGINE

While traveling home to Louisiana from a vacation, I noticed the engine temperature what stuck on Cold. We also were experiencing loss of power steering, and loss of AC in the car. We stopped at AutoZone in Destin, FL where they completed their FixFinder which reported the thermostat needed to be replaced, being it was stuck in the open position and wasn't properly gauging the engine temperature. Some of the engine fluids were extremely low due to overcompensation because of the thermometer issue. Seeing as we were traveling and not near our local mechanic or dealership, we called around to various auto shops to see who could fit us in same day. The only available shop, without having to spend an additional night in FL, was Pep Boys in Fort Walton, FL. They also let us know they did not have the thermostat compatible with my engine in stock, so that would need to be purchased at AutoZone if we wanted the car fixed same day; which is what I did. While we were at Pep Boys, there was another Cadillac xt5 there for repairs to their AC. It turned out, they were having the exact same issue I was having, but it hadn't escalated to the power steering yet. The mechanic googled the two issues and found there are known issues with the engine thermostat in this make/model, but there has never been a recall issued for it. Now Cadillac is refusing to reimburse me for the repairs because I was still within my Powertrain warranty (under 73k miles) but because we were in a hurry to get home from vacation to get back to work, we did not take the car to a GMC dealership, so the Powertrain warranty is apparently useless here. My extended warranty is also useless because the Powertrain warranty is still in effect.