Transmission (whine) Help?

[Heather Killgrove]

     I have a 2014 Silverado 1500 5.3 with around 42k on it. I’ve only had it for a year and have been in and out of the shop trying to get this transmission noise figured out. 
the dealership has said nothing is wrong with my transmission even though it slips and bangs in and out of gear all the time ( everytime I drive it) 

they have replaced the transmission pump and they claimed the noise was the belt tensioner but that has nothing to do with where the noise is located and that the noise is still occurring. The truck makes this screaming noise most noticeably when at idle. Then like I said before the rest of the time when driving the transmission slips ( it’s only been getting worse as. Time goes on) 

Has anyone else had this problem. And gotten an actual diagnosis? 
 The noise is just embarrassing and I want to figure it out before it causes more damage.

 

here is a video of the noise 

[pokismoki]

if the thermostat has never been removed in the trans , I would say your pump is trashed.  order a new pump, converter, and full rebuild kit.