»loging in and out in workshop

so i just joined the prison server and now am rank c, i worked my a** off to get 18 stacks of iron, went into workshop, put it all in to smelt and then some guy (a rather nice guy in this case) apeared next to me, he started taking all the iron. after a bit of talking to him he gave me 9 stacks back and he sayd he has been doing that by loging off and on untill he finds some player and takes all theyr items. pls fix