Snails are sods. I basically gave up back yard gardening after severe snail attacks killed most of the soft vegetables (courgette, aubergine, squash). Other than spending my entire time in the back garden picking them off and throwing them over the fence, I'm not sure what else could be done. Slug/snail pellets worked to an extent but the snails were so numerous that they would simply crawl over the bodies of their fallen brethren to get to the tasty veggies.