Transmission Stuck In Gear problems of the 2015 Kia Motor Sorento

When I turn a corner, my kia sputter to get around the corner. This problem has almost caused me to be in a couple of accidents. I advised the dealer before about this problem and was told, "my car is ok". This is not ok. Also, when accelerating, it sounds like the transmission or some other component is slipping. It rpms goes high before decreasing back down to get into next gear. I've expressed this to the dealership as well and was told once they drove my car, "they didn't notice any change". When going up a hill, I have to press all the way down on the gas to get up the hill which causes the rpm to raise and it sounds like it's stuck in a gear or something. These issues needs to be rectified immediately. This is not normal for a car to do this. It frustrates me to tell the dealership what's going on with my car and nothing is being done. I am the one who drives my car everyday and I know when something isn't right. How can a dealership tell you what your saying isn't correct when they don't drive your car everyday? for me to have purchased this car 1 year and 4 months ago with only 2,500 miles on a 2015 kia, I really shouldn't be having these many problems. It almost make me feel like the odometer was rolled back. Just my opinion.