your last bet is using a long craw bar jam it inbetween the flywheel ring gear and the gearbox dale,and other person use the breaker bar to crack the bolts,or hold on to the harmonic balancer and try to crack it..
Normally Auto starts to slip on top gear indicates your O/D is getting in the way,it will cause the hydrualic system to block up internally,matter of time before loses all gears..
Manual FTW..
Good luck
Not gonna last much longer,better save up and change a After Market Heavy Duty Clutch.. Try to Avoid Button clutches if you want to rev and dump,it will cause damage in long terms.
ER34 Clutch,pull type=not cheap..
Good luck dude..