Automatic Transmission problems of the 1996 BMW 328

I have a 328i BMW, and the information in the owners manual states that you never need to change the transmission fluid yet on the day in question my transmission began to stall and jerk. I than called my mechanic who I informed of this trouble, he then informed me to bring the car to him to check. I need to also tell that this automobile does not have a dip stick so there is no way to tell if the transmission fluid is going bad prior to what is happening to me. When I call BMW they informed me that they only warranty the transmission fluid and not the transmission, when you consider that the transmission only operates correctly when the fluid is right. In conclusion I would like to know if there are any other such cases reported and if so what is my course of action if any. Thank you.