The aluminium main hole cost
12" = 22.50 / 18" = 24.50 / 24" only 27

You not only need the manhole, you also need to purchase the metal bar (Furring Channel) / screw / "Mee Hon" / stopping ....
Hence is the RM250 covered all the items need to be use?

The labour cost is consider as 1 day rate even if they finish early, because people can't just dropby and do 1 job for you. Also, normal plaster contractor only do plastering and without paint for you.

If 250 covered everything, I guess still OK.

Indo rate is only RM100-150, but if you need to buy all the above than is that worst it?

Maybe you could ask them RM250 to include check + repair the leaking if only small issue?