sorry, should have explained properly. we got baited traps from b&q (would link but they aren't on the site) the bait is inside a plastic "box" so the boys couldn't get at it if they were foraging around. mice go in, eat the bait and its really quick acting, they are dead in minutes (seconds in the case of 1 mouse!) I didn't want the snappy ones, apart from the fact that we had tried that and the mice were just robbing the choclolate, i didn't want to see a squished mouse!
When we knew 100% where they were coming, we blocked that up too and have had no problems. We did forget to check the traps after we sealed up the hole though, one must have just been dying as we sealed up the entrance because the kitchen STANK and DPO had to move liquid mouse.
Would def recommend the traps. Think they are called baited mouse box (clearish plastic with green bait in)