apparently they are ridiculously easy to remove, some will come off just by giving them a good tug

as people have said before, loads and loads of peeps have had them nicked over the years so other than fixing them properly to the car there's not a lot else you can do other than actually glue them to the car

go on to one of the fiesta sites and ask if there is a preventative measure or if they can get hold of replacements, not cheap apparently which is why they go walkies