mohtballs do the trick, kept them away from my garden for months. you can buy them from wilko's very cheap in laundry section. just scatter around your borders or in soil but make sure no childen pick them up. hope this helps
Well said markasus. Even with a patrolling terrier we cannot keep the wrens safe, nor the bank voles in the rockery. Though I deprecate cruelty to cats or any other animal!