drill a hole right through the seat tube, quite a wide on maybe 6mm and find a rod to put in it cos you dont wanna ruin the screwdriver then heat it up a bit and twist and tug.. be careful not to damage the seat stay too much tho
ive already tryed that mate. dude this is soo stuck its unbelievable. wat its done is become prt of the bike. my mate has this bike now but we seriously have tried pretty much everything. i think im gonna cut it off and then weld a pivitol clamp on the end, blend it in and then powder coat the whole bike.