Where's my Shower?

One wall was taken down a few weeks ago due to a leak through the tiles. The joiner came to take the other two shower walls down because they don't have the same size of tiles to match the remaing walls. The joiner told me luckily this scenario happened as another wall was fully soaked through! The tiles came of really easily apparently and you can see it in this photo, black marks - mould and what you're looking at is the second layer of plasterboard.

So the water managed to get through the tiles, a moisture resistant plasterboard and then soak through another plasterboard underneath! Lukily there was a foil barier underneath all this. The water did not penetrate that or else the insulation would have been water logged too. The joiner said it must have been like this pretty much at day one for the boards to be soaked through like that. I'm no expert but that sounds like a badly tiled or grouted job from the start?

Tomorrow the tiler is coming to tile the new wall. Luckily this is all covered under warranty!