I've been painting a wall for what seems like a year. The process goes as follows. I clean out the shallow pits/ marks, then fill them with polyfilla, then sand them, then roll them with a matt water based paint. If the roller doesn't pull the polyfilla off, they soon bubble out and crack. I've tried using plasterboard adhesive as well, but does the same thing, I've also tried a brush, same problem. Maybe the wall underneath is 'breathing' or something (lime rubble)? Then I have caulk along the top of the skirting - which doesn't seem to want to take the 'wood and metal' skirting paint. Keeps chipping and flaking. Any ideas at all, have also tried valium but hasn't worked.