Name and shame if they are cheating and not going to controls. I did this at the SLMM a couple of years ago when running with my son as he was furious in the way that kids can be. Lady of the mixed pair said she was injured- i said that was fine but presumably as injured did not expect to win! Planner and organiser upheld my complaint
This weekend I had my own dibber but opted for tyvex so I couldn't lose it. having said that I can often pull it over my wrist as they put it on so loose (never have- but could)