I mentioned in my initial post that I've attached a note on the front windscreen and in fact, if I've known the culprit, I will bring a box of fresh durian fruit and knock on the door.
@Wylie, they all looked like a logical point of escalation. What is the timeframe you would want to wait before boiling point ? 1 day, 1 week, 1 month, or 1 year without escalation.
Well... if you are reaching boiling point, do it NOW. If you do indeed have a "dedicated" parking spot for your particular unit, and the body corporate will do nothing about this person using your block of units as a free parking spot, then take matters into your own hand, and install a bollard to keep "your" park for your own use.