When thinking about customer service in big companies, it's important to remember that the vast majority of calls legitimately are of the sort that only require a very simple action to be taken, and then to be disconnected as quickly as possible. However frustrating, it's not irrational hatred of customers that makes it difficult to break through that assumption when you do have a more complicated issue.
Many years ago I was having trouble getting some accounts closed with NatWest (after a few cockups on their part already I moved to FirstDirect). I happen to work for a company that produces compliance software and offered related consultancy so we had copies of the FSA (then new, since reformed as the FCA) complaints manual lying around.
After months trying to get traction on the closing the accounts (including warnings of charges because one of them was "under funded" by virtue of having been emptied because I wanted it closed) including a couple of face-to-face meetings in the branch (back then little was done remotely), everything magically sorted itself out after the day I went in and read from that manual while waiting to be seen...
It isn't just "others noticing": any sort of fallout gets things more noticed.
In hindsight I had a case to just go strait to the authority about it and probably should have done. The bank would probably have got a five grand fine and I might have been compensated for my wasted time...
I mostly do it because it saves me driving in and/or waiting on hold, but those messages usually seem to be answered by the same team (and are generally handled very well).
Which is one reason why tweeting works well (or it does if you have enough followers). I've had great results that way from several firms, though I have not tweeted to Apple.
They don't seem to care unless there's a chance of other people noticing.