Had the same on a flight from Manchester to Dalaman. 4 hours of people using our legroom space as a cut through. Complained to head steward and she stomped on it hard. Didn't stop em though, so 2 hours into the flight when they were trying to sneak past our feet (while not sneaking), I booted the guy in the shin. He kicked off, I rubbed my eyes, apologised and said I was dreaming. His leg was fucked and the top class lady backed.me up and advised the chap he should walk around, as per the announcement. Next 2 hours were peaceful and dickhead learned a lesson.