Wiring problems of the 1999 BMW 323

I own a 1999 BMW 323i. Recently, the check engine light keeps coming on along with the sign for the transmission (the exclamation in the circle). Then the power was significantly reduced which didn't allow me to drive over 40 mph. I took it to the BMW dealer near my home and after they ran the expensive diagnostic test they still weren't sure what the problem was. However, they said they received a bulletin from BMW telling them that resetting the computer for the torque and transmission would fix the problem. However, this was only a temporary fix, as it only lasted for one week. The light still came on and they still don't know what the problem is. This frustrates me that the BMW dealer doesn't know what the problem is. I know of several other BMW owners and they have the same problem. They all have traded their cars in for a Honda or some other japanese made car, which I am considering too! however, I shouldn't have to resort to this, as I have spent a lot of money for this luxury car and would like to keep it. Nevertheless, I believe this is a manufacturing problem, as many electrical problems among others have been reported by BMW owners and dealers. A CO-worker's had a '98 325 and had only about 70k miles on it and she had major engine problems and spent about $3500 dollars and the problem still wasn't fixed. So, she trade hers in for a Honda. I spent about $400. 00 and my problem is still not fixed. I am hesitant to pour any more money into fixing my car especially, after my friend spent much more and hers wasn't fixed, and when the mechanics aren't sure what the fix is. I believe this is an across the board type of problem with many if not all BMW's and the manufacturer doesn't want to admit it. Just go to Bmwcomplaints. Com to see for yourself. I would like an investigation into this problem and a recall to fix these serious problems.