Really starting to dislike mice

I always have an ongoing battle with the mice in my garden. Their latest stunt was to go through the 24 brassica plants sitting in my coldframe and neatly nip off the top of every single one of them. The coldframe just has to be moved an inch in the wrong direction and they can wriggle underneath it and have a party with whatever happens to be in there. 

My sympathy - I have them too. I see my veggie patch as "one for the mice, one for the slugs, one for me....one for the mice, one for the slugs, one for me...".