French door opening and concrete cill issue.

[24PoW]

I'm currently enduring a drawn out saga with a builder who's meant to be fitting a french door to the rear of our house. He's cut the opening for the door but, by his own admission, he's messed up the measurements (he had to change the lintels he fitted because there was inadequate bearing at either end). The doors arrived a few days ago and the fitters quickly pointed out that the opening he's cut in the building is too small - so he's now got the Stihl saw out again to have another go at our building. What we're left with now are 4 really ragged cuts. The building is 1920s and it's lime mortar that holds the brick together. As you can imagine, the relentless chopping hasn't been kind to the bricks, and some of them are in bad shape.
I've now noticed the new 1500mm concrete cill he's fitted appears to be too short for the door which i'm measuring at a width of 1590mm. To compound this, he's also not taken the floor screed or flooring into consideration and the new cill sits level with the original (extremely uneven) concrete floor. His plan now is to pack and lift the door by fixing tiles(?) under the door to gain 20mm. He says there's 15mm to play with at the bottom of the low threshold door, but that takes us right up to the bottom edge of the door. The doors open inwards btw.
This is just turning into a complete disaster as he battles to get these doors to fit .
Should the cill extend beyond the width of the doors? And by how much?