general problems of the 2005 BMW 325

My car's transmission light came on so I pulled over to the side of the road. I turned the car off and on but the warning light wouldn't go away. After the car was turned on, it would not shift into drive even though I could hear that the engine was running. I had to have the car towed and was informed by the dealer that my transmission would need to be replaced. This would cost approximately $6,500-. It seems that several BMW owners have had similar issues with the transmission. This is a huge safety concern since I was on a 2-lane highway through mountains without any cell phone reception.