Open burning

Can anyone tell me what one should do if your stubborn and inconsiderate neighbors do open burning? I happen to have 2 backyard neighbors who openly burn their stuff almost every other week, the most recent ended with my grounds showered with their ashes. Despite my polite request to stop it, the resident continued the following day, and same stuff ended on my grounds. I am pissed. My area is Piasau Garden. Anyone sharing my views and any advice?