Agree with all above. The fixing is terrible. Would just like to say regarding the grout lines, they are a bit small for under heating(2mm). I would go up to 3mm(BSI) or 4mm. When you get the work redone. Hope you get it fixed.
Need glasses i think. It does look like it's 3mm spacing but in the close 1 it looks like it tapers from the centre off the 4 tiles.