how to prepare surface – flaking acrylic paint from enamel and plaster?

cal_blam

My apartment renovations are grinding to a halt…the bathroom had no extraction fan and previous owners put acrylic paint over ceiling and walls. The substrate was enamel paint atop plaster walls/old plasterboard (1940s) ceiling. Its now flaking and when scraping, chipping through to the palster board in some places. Am very keen to egt the acrylic off ASAP. Its a real job every few days more flakes appear. Can I use a heat gun or will that be very bad for the plaster? Alternatively should I strip it back with some sort of chemical? Sanding is taking far too long, as the enamel wasn’t that smooth before they painted over it. Do I need to just scrape as much off as possible then resurface it with jointing compund then paint over the top again?
Any helpful suggestions would be most appreciated. Cal.