I've been to 5 dealers in Southern California, the 18's have always been standard and of the like 10 135s I've seen I haven't even seen one with the 17s. I would find a different dealer. I've spoken with Sonnen BMW which might not be too far from you in San Rafael, and they were pretty straight forward and knowledgeable and actually had quite a few in stock, including a silver in stick which I spoke to them about.
Try Chip Rutan at
chip@sonnenbmw.com or 415-601-2497. They also list their inventory at cars.com and might on their website as well though they don't give much info. Hope that helps. I know from experience how frustrating the process can be with these 1 series cars as the dealers tend to give out a lot of misinformation and don't really know much about the car or the options or ordering process it seems.