2005 MERCEDES E500

My Mercedes seems to be stuck in "stick shifting" mode. I have tried calling the closest Mercedes dealership to ask them how to change it back to automatic mode and they were no help. All they could tell me was I needed to bring it in and it would cost at least $150 an hour to work on. So I decided to try and look it up on the internet and you tube. Unfortunately I havent had any luck. I already did a transmission reset on my car as well as unhooking the battery for a few hours and still no progress ? when I drove it it didn't seem like it wanted to shift into a higher gear either. Any suggestions would be greatly appreciated!! Thank you all in advance!!! ❤