I took my 2012 Sonata GLS into the dealer for a whining sound that had progressively gotten worse over a couple of months. They ran a diagnostic($130) and advised that I needed a new transmission with no further explanation. So I asked more questions and they only had 2 ideas. One was a bad bearing and the other was the planetary gear pack. Which doesn’t make any since to me because of the type of noise it is. It sounds more like a fluid restriction whine. I did have the transmission flushed but it did not help.
Find an independent transmission shop ( not a chain store type ) and get a second opinion .