Could be anything from tie rod, wheel bearing, lower wishbone, tension rod, sway bar link, strut, and sway bar. Take it to a good INDY since the dealer visit was worthless, or jack the car up and look for yourself. I hit a pothole once (i could feel wheel vibration through the steering wheel) and the dealer said nothing was wrong, but my tie rod was frozen. I jacked the car up and found my sway bar shifted so I replaced the bushings and I was about to purchase new tie rods and install myself. The dealer said they wouldn't replace my tie rod due to my aftermarket coilovers. I contacted BMWNA and they were great about it, they were going to reimburse me for the tie rods (since I was under warranty), but I sold the car and made full disclosure to the new owner. BMWNA said they would cover the tie rods for the new owner and what do you know, the dealer had a new Service Director the following month. So, your dealer could be playing stupid to avoid replacing any damaged parts.