I have a double passenger seat in the front of my van, the seatbelt catch in the middle is a bit of a pain to get done up. Just after peoples thoughts/ experiences with belt extension pieces. I have seen 1 that plugs into both catches on the seat and also 1 that plugs straight in and extends it up a couple of inches. Are these safe to use? the first 1 is £40 which i think is a bit expensive but cheap as long as it works effectively