BMW Repair: Heater, gm transmission, speed issue

Question
So my heater or air condition. Does not matter what one i use it decides on it's own what speed it wants to come out?? What causes this? Do i need a new blower motor? I have come to find out as my car has more and more problems. No one but the dealer can work on these cars.One night i go to move my car and  i have no reverse so now i need a new tranny. As i find out this happens in a lot of 2000 323i... Also have you heard anyone fixing the reverse gear without having to put a new tranny in? I went to one tranny place and they said they could fix it for like 2,000. Another one said they didnt know cause they can't hook it up to the computer but the next day they told me i need a new tranny. Called BMW and they said i need a new tranny 5,000!! And that BMW does not rebuild they only replace and that they don't make parts to trannys thats why they just replace it. It's starting to look like you can only take these cars to BMW since no one has a computer to hook it up to and no one wants to touch them.. I work for AAA of NY and whenever a BMW breaks down no one wants to touch them or work on them..  

Answer
Jessica, this is very often the case with BMW. You need to find out whether you have the ZF (german trans), or the GM trans. The reason being is the ZF trans has little hope of rebuilding instead of replacing it. The GM transmission is basically a 5L40-E General Motors transmission with a BMW bellhousing pattern. You might have a shot at rebuilding it or speaking to someone who is knowledgeable about rebuilting. True that we don't open up transmissions at BMW. They are sent back to the vendor to be rebuilt. Notice that we don't make our own transmissions. As far as the blower motor speed issue, you need a new final stage resistor. Usually close to a 90 dollar part at the dealer, but you can get it at other online parts houses. It pays me about an hour and a half at the dealer to replace. The instructions are all over this forum but mainly in a post to a guy around 8/24/06. sorry for the bad news on the trans.
-Evan