Mrs. FF and I once paid for specific seats on an EI flight from BFS to ACE. When we got on board, the entire row was being mucked up by an elderly couple who had been allocated single seats when they cut it fine for check-in. They simply plonked themselves down in a window and a middle seat and refused to move. We had reserved the aisle seat and the middle. Another couple had reserved the aisle and middle on the opposite side. The elderly couple just ignored cabin crew requests to free the seats. They wanted to sit together and that was it. The other couple in the row were moved towards the rear of the aircraft and we got the aisle and middle they had been occupying.