Hi Jo I had exactly the same problem with our 2006 focus that had two piece rear backs and seats. I got a full set of covers from Lidl at the time. The rears were what they call a 60 - 40 split, that,s to say 2 pieces for the seat and 2 pieces for the back. You then install them so the joining zip of the 60 piece, the longer one is by the seat belt and the 40 the short one, on the other part of the seat back. When you zip them together you can pull the zip up so it allows the seat belt and buckle to remain on the outside of the cover but it will not allow full close of the zip because of the belt reel holder.