Thanks w7_lee for the advice. Yes my painter and electrician are separate parties.
Just sharing for the sake of other forumers doing electrical works - I made a big fuss and made my electrician come back to patch up the big holes. The painter made it clear to me that they will only patch the holes left behind by screws, nails and some minor cracks due to age, but not leftover damage from dismantling fixtures/wires/casings.
So do take note before paying your electrician.