after trying most of the reccomended products to remove citadel paint, eg brake fluid, pine disinfectant, turps etc, I have to say that the one that worked the best for me is the one I least expected to, The product in question is DETTOL, you can get it from any decent shop for a couple of quid & it will work on plastic or metal miniatures, I tried it today & it didnt take long                  (couple of hours) & the paint was loose enough to attack with a toothbrush, need to leave it in for a bit longer to get into all the nooks & crannys.

So there you go, get yourself some DETTOL, the most unlikeliest citadel paint remover.