what you must remember is that you mustn't "cut your nose to spite your face" no matter how upset you are with bmw.
in other words, by kicking bmw in to touch, you may be doing yourself a disservice. dont leave the bmw brand just to teach them a lesson. you may end up upsetting only one person - yourself. there are some good bmw dealerships out there. take your pick and get that bmw you love.