BMW / Bayerische Motoren Werke review: un-skillful and bad service

I experienced my BMW 325I consumes oil but it was driving well; I just needed to add one quarts of oil every two weeks for the past few months. I decided to bring it to BMW of Bellevue for service. They told me there are a few things related to it, the valve cover, filter housing, and drain hose. They also suggested me for other fixes. After I spent $2, 600 for the car and took the car back for two weeks the low oil sensor light back on again. The oil consumption problem is still there. I brought back to the dealer again. They added two quarts of oil and do the diagnostic again. This time they said I need a new engine that would cost me $15, 000. It's a 2002 car; I don't want to spend $15, 000 more to fix it. I asked them to refund me the money they charged me for the problem that never get fixed. But they denied to refund the money. I brought the car back for a few days now my car stopped operating, not even start ignition. I don't know if they did something wrong to my car or something else. I talked to them and all they said it's not their problem. I'm very disappointed at this dealer, BMW of Bellevue. I would not recommend anyone to their service. I would not consider another BMW because I don't want to deal with this kind of service again.