Treat them the same as you would slugs. You can try a beer trap or put down some slug bait such as Sluggo.

I had them everywhere then got some carnivorous (decollate) snails. I have had only a few now for about 4 years. They eventually die out themselves.

Do any of the nurseries carry them? I don't know, had to order mine online.

a really cool website. They include decollate snails.

Here is a link that might be useful: snail control

I have the decollate snails in my garden, but never had to buy them. They're just hanging out in my garden. I suppose that is why I don't see too many of the other snails or slugs! I must have enough of a food source for them.