Just thought I would add a recent experience for those looking for Sydney based independent BMW service, and this looked like the thread.
Our 3 series wagon started making a clank noise from underneath. A few hours surfing the web had me pretty convinced what it was. I then hunted around the forums for a non dealership recommendation in my area of Sydney. Two popped up.
1. BMWise Artarmon -took the car in, discussed the problem with the mechanic (not the owner). Got a call that afternoon saying the problem was the differential and it needed to be replaced for $3k. I then told the owner that in fact it was not the diff, rather a related and relatively well known problem -even gave him a parts list for the repair. He insisted that BMW told him that you can't work on the diff, it can only be replaced. To which i again advised it was not the diff. Needless to say I took the car away, having paid $120 for his time (which he would not budge on) to tell me what the problem was -even though he was compeltely incorrect. This guy is supposed to be a BMW expert, what a joke -maybe ok for an oil change but otherwise don't bother.
2. Then rang Peter Mabey Car Care and spoke to Greg. Explained the issue, to which he said yep know what it is, but drop the car in and I will double check. Did this a few days later, probably 30 seconds after jumping in the car he confirmed the issue. Fixed in a day for $700, exactly as expected from my prior internet searching. Great experience all round, good communication, good workshop, highly recommended (albeit not cheap).
Hope this helps people in Sydney north area.