I was on a run of work trips a couple of years back that involved a LOT of flights. I repeatedly selected seat 2C. Except for that one flight where it wasn’t available, so I selected seat 2D instead. After 12 days of boarding flights and sitting in Seat 2C, I rocked up to 2C and found someone sitting in it. Said it was my seat, asked them to move, and they did - to the back of the bus.
On day 14, same thing. Boarded and someone was in 2C. Ok here we go again, I thought. However, I politely enquired if they were in the right seat, and they assured me they were. Pulled out their boarding pass and showed me - 2C. Oops, this was my turn to try 2D
!
I apologised profusely, and took seat 2D with my cheeks absolutely flaming. As it was quite a long flight, we had some time for a longer explanation across the aisle, and I must say he saw the funny side of my attempt to evict him from his seat. It’s made me paranoid about checking and re-checking my own boarding pass before trying to take a seat, that’s for sure.