I am having successive problems with my car. Is it the BMW Service Center?

What is your question?

My '01 325xit has been nearly trouble free for 189,000 miles. (Two window motors replaced as stated in the other comments.) It was running great, until I brought the car in for brakes and an alignment, and they found the oil leak (mentioned in previous comments), told me I needed a new compressor (a/c was working fine), coolant hose replaced, oil pan leak (in addition to the one above. This was $4274.92. The next week, 140 miles later, the alternator went out. They admitted it was partially their fault because of the solution they used to clean the engine, but that the alternator was "old". $500. Two weeks later (and 400 miles) , the car started "chugging" and could barely accelerate: new spark plugs and ignition coils on all 6 cylinders. $1095.00. Now the "Service Engine" light goes on and off, the car "chugs" again on and off, and it seem to slip/miss/or backfire at times when I accelerate from a stopped position (but it has also occasionally done this on the freeway). Are they screwing up my car?