Cracked Floor Tiles

[Firsthome1]

Hi, and thanks in advance for any advice I can get from anyone.

I moved into our new build home May 2019. There were many internal defects, most of which were sorted. However we’ve had 2 big issues.
 
The first being that, the shower in the en-suite was leaking, this was raised immediately with the builder, and someone came and apparently "sealed" the job. However around Christmas 2019 I noticed black mould and fungi growing from the skirting board that connects to the shower. I raised my concerns with the builder, as I suffer from a severe respiratory condition, as well as an infant baby so having any damp can worsen my condition and potentially cause my child one.

When he finally came out I was told that it's not damp and just needed to be painted. It was only when I spoke to the developer that he came out and noticed the shower hadn’t been sealed correctly and so for the past 9 months water had still been leaking into the skirting. Someone has come to fix the shower now but nothing has been done about the mould on the skirting I was again told it just needed to be painted.

Since I have rearranged my spare room I pulled away a piece of furniture only to find that the skirting board adjacent to the en-suite has also bubbles as has the same black outline of mould. I have again mentioned this to builder, but he insists it isn’t his problem to fix and now ignores my calls and texts.

Secondly, a crack has appeared between my kitchen/utility along 3 tiles, about 6 months after moving in. I mentioned this to builder and he said that tiles aren’t covered in warranty and expect more because it happens due to setting cracks! (I certainly wouldn’t have chosen tiles if I knew this prior)
I have since had several different tilers down to check, who have said that it is actually to do with the levelling of the floor, and cracks in tiles can be avoided with proper planning of joints etc. I have also rang the place I chose my tiles, and was told they are discontinued. My argument is that is is poor workmanship in that case and I shouldn’t be responsible for replacing it.
 
Furthermore my concern to this is, my sister in law lives 5 houses down and has seven/eight cracks in her tiles around the kitchen and I do not want the same happening to ours, or be responsible for replacing the entire downstairs. Again they have not responded to any messages or calls.

I appreciate settling cracks can happen, but in this case it doesn't seem that’s what’s happened here.

I am just looking for any advice in resolving my issues with the builder. And if the tiles are actually my responsibility or not.

Thanks

[New Home Expert]

First rule here is NAME THE BUILDER!
This is to warn others what to expect if they also buy a new home from them.

The cracked tiles are your problem only if you paid for the tiles and for someone to lay them for you independently of the housebuilder.
Whoever laid them, should have levelled up the floor first with latex.

All damage caused by or from a plumbing or water leak should be rectified by the housebuilder.
The skirtings are MDF and once they have been wet must be replaced. Just repainting is not an option. 
All areas potentially affected by the leak(s) should also be investigated for damage ie flooring and joists, ceilings etc.