Sorry it’s a long one as looking for some advice please. We have had 50sqm of 600x600 porcelain tiles laid in our house which there is movement in the tiles. This has resulted in some lifting and grout popping out in places . Method that was used by them, 6mm ply fitted to existing floorboards then some sort of pvc primer/sealer? Rolled on top of the ply, underfloor heating mats were then laid on top of this and a self levelling screed over the top which finally the tiles were then laid on top of. Haven’t used underfloor heating yet as grout started popping out and tile movement also began happening before the time passed where we would be able to turn it on. Basically where we’re at is we have been back on to them to try and get this resolved. After some discussion and debates we’ve now been told that all existing tiles will be lifted, a new screed put on top of existing one and new tiles fitted on top but will use a different adhesive this time. So the question I have is will this actually work? Or is there anything that we should be aware of that hasn’t actually been done correctly with the method/materials and should be done differently?