Transmission took a S*&%
 

Ok so let me start with I have a 2000 lesabre limited. I started hearing this whine coming from engine area after getting oil changed at an oil place. They said the tranny fluid was low and topped it off. That was June 29Th. Today while driving to work I noticed it hesitating a little and stopped at a light. when the light turned green for go my car wouldn't. It just revved with no movement. Engine starts and runs fine but I have nothing in any gear. Not even reverse, I am not sure where to go but I need to get it fixed. Anyone have any clues.? I know that my buick manual calls for dex 6 trans fluid. But on the dipstick it says use only dex 3. My dad had the car before me and he always used dex 3 on changes. Could the oil place have pulled up specs on car and just put in dex 6 and could that have done this? I am probably reaching but I am not sure what to do. Thanks in advance for any help

Before you do anything, check the trans fluid level.
Anything is possible. It might be a good idea to remove the pan and change the filter and fluid . Then see what you get.