"...I had to resort to contacting the President of BMW to finally fix the annoying noise at the back of my BMW..."
good that you stuck with it 'til the issue was resolved.
from what i can tell, it was a case of two hard plastic pieces rubbing against each other; nothing that a "gasket" or a shim couldn't fix.
the fact that you got sub-standard attitude from BMW Toronto doesn't surprise me. I stopped going there about 6-7 years ago.