Do not pay them until you verify what you are getting with people here. A lot of local shops do not know what they are doing.fair enough ill see what they can do.
^^^^^Thank You!!!! Seems like no one every pays any attention to what was actually posted. You clipped the HELL out of those subs and amp. First of like was stated above, get those gains properly set and the polarity correct. I would def get a box built to spec, do away with the cap(waste of money) and the only other really good suggestion I saw here was to cut out the ski hole, this will make a huge difference. Bimmer's are sealed up pretty good, someone also mentioned the big 3 and this would be a good ideal in most other cars but I'm not really sure how much good it will do you in your E46 cause it may already be done from the factory, my E39 has 0ga from the factory so you may want to check.This thread is full of bad advice from people who didn't even read OP's story.
First if you broke one of those subs off a 1500W amp to the pair you're definitely clipping them hard. Really that's quite an accomplishment to break a 3" coil on 800W... you should be proud!
Next, if they sounded good and you replaced one and you have almost no output even with cones moving, you hooked one up reverse polarity.
Finally if the box is buzzing unless you press on it it has a broken seem. I'd say you could probably repair it, but it may or may not be worth the bottle of glue and handfull of screws.
The point being if OP was happy with the sound until he blew a woofer than he really doesn't need anything but to hook it up properly, figure out how to not break woofers from gross abuse, and repair or replace that box.