Deden's do fix boxes,but as you have a broke box how do you know your collars are broke as well?.Test them with another box before chucking them,very rare for everything to stop working at the same time mate,would think it will be one or the other rather than both.I have a broke collar that only reads at half the depth with a fast click,same as a flat battery,but took them to deben's (only live a few miles away)and they tested them all for me(2 boxes,3 collars)cost me a tenner and they sent them back to me within a week.