In 1998, I bought a 1991 525i (E34) from the original owner with 54K km on the clock and a full service history (or so I thought). In late 2001, I was driving home from south of Munich when the car went into limp home mode with a transmission error. I learned that if I shut down and waited five minutes, I could drive another hour before the computer put the car in limp home mode. This was not a fun 6-hour trip.
I took the car to the BMW dealer in Darmstadt, and they confirmed there was a problem with the transmission. My only option from the dealer (or any dealer) was to replace the transmission. If I wanted a factory new transmission, the cost, including labor, would be about DM 10,000 (Germany had not converted to the Euro then). If I wanted a remanufactured transmission, the cost would be about DM 6,000. When I asked why they couldn't repair the transmission, the answer was "we don't do that, we repair by replacing." I then asked where the remanufactured transmissions come from, since this implies someone is capable of repairing them. The service manager didn't know since all of the transmissions are sent to a BMW depot, but he knew there were only four or five shops in Germany that rebuilt the transmissions for BMW.
I had a second car, so while I decided whether to dump more money into the BMW or cut my losses and scrap it, I saw an advert in the German paper for automatic transmission repair in Heidelberg. I spoke with the owner and he confirmed that he might be able to repair my transmission, depending on the fault. If he couldn't rebuild it, he would replace it with a rebuilt transmission he had in stock. Either way, the maximum cost for parts and labor would be DM 1,650. This confused me, so I told him about my conversation with the dealer and asked how he could do the work at a lower price. He told me he was one of the shops BMW uses to rebuild the transmissions.
I dropped the car off at the shop in Heidelberg and waited. Two days later, I received a call that the car was ready and my cost was DM 150. The mechanic researched the service history and discovered a factory recall for the transmission that was related to the fault and the original owner apparently ignored. BMW honored the recall and I received a rebuilt transmission for the cost of fluid and shop materials and a two-year warranty on the transmission. I drove the car for another 12 years without any problems before giving it to a Soldier.