Filling holes so you can't tell...

[Pupp]

Have removed a couple of bannister rails that were fixed to a plastered wall, and am struggling to satisfactorily fill and smooth the resulting impressions that were left by the round brackets.... seems like no matter how much I fill and scrape/sand, there is still a round telltale coming through. Want a white satin emulsion finish and this seems to show every imperfection. Any ideas?

[Pupp]

Cheers all, trying to get interested again. DIY is a vastly overrated passtime