Or save yourself £3.95 and just get a massive piece of cardboard, a thick marker pen and write your own. Ensure the cardboard sign is so big it fills the entire dash, ensuring even the most unobservant technician can't miss it. That plus a luggage label sign on keys, instruction written on worksheet and highlighted with highlighter pen (bring your own if necessary, lol) and verbal instruction to the point where they live in fear of you. That does the trick.