New Double Glazed Windows onto old windowsill - question

We've just got new PVC double glazed windows fitted. They were fitted into the existing window gaps, replacing old Aluminium double glazed windows.

On the outside, where the old windowsill comes up vertically but not yet up to where the new window sits, there appears to be a rough gap. About an inch high.

The new windows also sit slighly forward of the vertical bit of the upward part of the old windowsill (because it's worn away and rough). This upward bit of the old windowsill is unfinished - rough crumbly concrete.

I gather the old windows had a lip coming down that covered this bit and that came down to the horizontal bit of the windowsill.

Should the new windows look like this? It looks like I need to get plastering done underneath to improve the look where of the space beneath them but above the horizontal bit of the windowsill?

Should this have been done as part of the window being installed? Thanks.

I would be calling the company back to finish them properly, it sounds like they didnt measure the gap properly, they should be flush fitting and sealed onto the old windowsill and should have a pvc strip to the front of the window overlapping the lip on the sill to ensure rainwater runs off.