Delta Air Lines and United Airlines were sued on Tuesday by passengers who claimed they paid extra money to sit in “window” seats, only to find themselves placed in seats next to a blank wall.

On these types of aircraft (as well as several others), the cabin window lines are interrupted by the existence of air conditioning riser ducts, window conduits, or electrical wiring embedded in the cabin wall, which makes placing a window there impossible for the manufacturers.

A new complaint filed against United and Delta Airlines on Aug. 19 accuse the airlines of deceptive business practices and false advertising.