Any help? Stem seems to be stuck - Seized quill stems

Oh you mean really stuck... I got a total bastard out once by turning the bike upside down clingfilming the hell out of the headset/ stem so it was watertight and then pouring coca cola into the headtube and left it overnight. The next day: bingo!
coke is also great for cleaning your bog! 2 liters of el cheapo lidl coke = shiny pan! :-) all the best tips on LFGSS.