I haven't had the refridgerator magnet type, but I have had the flat vinyl ones (which they insist to put back on after my first service visit, they now have a big note in their system that if they do it again my car is getting detailed for free

) I used a hairdryer and a plastic spatula to take mine off. The hotter you get the decals the better, make sure you heat it from all angles. Do them one by one, start at one corner and they should come off. Any residue left over take off with GooGone or something like it and then rewax the entire area because the Goo Gone takes the wax right off too. Hope that helps