Flashing under window sills

[Avemal]

Seeking advice.

I had the flashing on my extension roof replaced in mid March after a leak in February.

I've attached pictures showing a before and after. The height of the flashing up the wall was increased and cut into the wall at 25mm depth. Does the flashing around the window sills look OK?

Another issue is the sills themselves. In order to have the flashing the correct height it looks like the roofer cut into the sills. Was this a good plan? The sills had cracks in them already, but cutting into them has damaged them further. The roofer is coming back tomorrow.
What is best way to fix the sills?
Dig out and fill or completely replace?
Having thinner sills to allow flashing to go underneath?

Any help greatly appreciated.

 

[catlad]

The problem lies with the person who designed the roof not the person who is trying to sort it out.

 

[oldbutnotdead]

Your roofer has done their best with a rubbish set of conditions- whoever designed the extension should have set the roof so it could be properly weathered under the windowsills.
Would have been better to replace the windowsills before reflashing the roof but you are where you are- scrape the paint off, fill the cracks with car body filler, repaint. Mainly to prevent water seeping into the cracks & getting behind the new flashing or freezing & spalling the sills even more