Help/advice needed re: immigrant workers to the uk?

i have noticed in work that we are having to replace the toilet seat every other week because someone keeps breaking it and leaves footprints on it , also the wall gets pebble-dashed most days , this has only begun happening over the last couple of months since we imported some cheap labour to do some crap jobs that not of the locals want to do , do we need to get a doctor to help out ? obviously someone isnt well , but i dont want to question the imports as they might go and work elsewhere ? your advice needed