Firstly welcome to the forum..
Electrical problems can be very tricky at times. It looks like it's safe to say that you have an electrical short somewhere. I would say otherwise if it was an isolated incident, but it clearly isn't. I would check to see if all your fuses and relays are in working order. Once you find that they are, or are not, then replace the ones that are not, and see if they blow again. This will at least indicate where the short is coming from. If they are all good to begin with, then you may possibly have to check the wiring harness for the affected part to see if any wires are kinked or cut.
Good luck. It doesn't sound like an easy fix, but i hope i'm wrong.
BMW...Now you're playing with power.