2022 Buick Enclave Engine problems

Due to an inability of the Buick auto manufacturers to provide parts to my 2022 Enclave, after becoming disabled to drive in auto accident..since November 27th, enduring a 3 month wait with rental car fees, and emotional stress strickly because unable to obtain parts! How does a company sell a car without the ability to pro ide ANY customer service in a timely manner.. I've made 4 car payments with no car..I purchased a Buick with the expectation of quality service..

Mounting bracket for exhaust in front develops a leak at a cross member. GMC is aware of the issue and has refused to honor their extended warranty for the 2021 model year on my 2022 Buick that was delivered in 2021 due to mileage even though the extended service plan extends mileage to 150,000, mi and 15 years. Vehicle has exhaust leak which triggered check engine light. Could also possibly cause carbon monoxide poisoning

Engine revving, would not shift even after taking my foot off the accelerator. Had to pull over and shut the car off. After restart, it was very hard shifting but the engine wasn't revving, Engine light stayed on. Engine revved between 3,500-4,500 rpms without shifting. The car can be very jerky when accelerating from a stop and shifting the first time or two.