This can be tricky, even for experienced technicians. The best bet is to buy a repair manual for your 528. You'll find detailed diagrams and instructions for how to find the fasteners and how to take off the panel. Another good resource are BMW enthusiast forums--you can find car-specific how to do it yourself information.
Ahhhh leave it broke. It will just break again. It's plastic for god's sake. Wait till a cold day with a little ice jamming things up.
BMW has put break away cables in all their doors. The technicians are very good at disassembling the nice wood trim and the rest of the panel. They need the work. They stock the extra parts to git the job done. Particularly in the winter when they're supposed to break.
ok, this is actually an easy repair. Nothing tricky about it. go to bmwrepairkit.com follow the link to the video on how to replace the window regulator. It shows exactly how to remove the panel in addtion to replacing the regulator. Less than a 7 minute job.
There is a star screw in back of the handle, you have to remove the little circular plug, then there is another screw philips head up near the vent real tight against the circular vent itself take that out, then the rest of the door just pops off, twist the black cover with your inside handle to the inside part, now you have access to the cable, sometimes it just comes off the handle itself, just pull it onto it, sometimes lifting the outside handle at the same time gives you more cable stretch, good luck