Water bottle thrown at me by driver angered at having to wait to overtake

If you really want to make a nuisance of yourself, you could make a data access request to see what's actually been done, and make a formal complaint. I did that last year when I was really unhappy with plod (not in connection with a cycling incident, but quite a worrying one involving a direct and apparently earnest threat) and had a phone call from a senior officer within 24 hours enquiring as to 'how we might resolve this at a lower level'. It ultimately go nowhere, but I suspect it made them look at the whole thing properly.