I have to agree with Dissembler, I'm a tech at a volkswagen dealership, and I assume the warranty on squeeks and rattles is the same as ours which is 1 year or 20k.
Is that fair? I don't really think so, but does that mean that the dealer has to fix it for free? NO. I know it sucks, but that's the car manufacturer deciding not to warranty that type of concern, not the dealers. The fact that they looked at it at all and attempted to fix it show's they were trying to help you out.
You should have done your research before buying your vehicle and seen that bmw does not cover that concern and is not responsible to fix it, thats part of the deal you made when you bought that car, you agreed to the warranty that it comes with.
You simply cannot expect a tech to spend alot of time on something they will not get paid for. I don't know about you, but I don't work for free, I have bills to pay and I need to make money while i'm a work to do so.
I understand your not happy that they did not fix it, but i'm sure you were told that this type of concern is not covered under warranty, if they did not, then they should have, and they should have told you that if you wanted to get bmw to fix it, to call the after sales guy and complain about it. To me it sounds like the service advisor tried to help you out and attempted to solve the issue for you, but after trying once, they can't justify to spend more time on it. Likely would have been better for them to not help you at all, and direct you to call after sales and have sorted it out that way from the get go.
I have to say I really hate the mentality of you spent 50k on a car it must be perfect in every way, and that everyone must do everything for you immediately for you regardless if they are going to get paid for it or not. As far as I know a 3 series does not come with a slave.