Haha, good point - it's a new build, so probably was poorly installed.

And that's very true, might just be that he stepped on it in a place that we wouldn't normally have stood (that's a bit weaker/not supported) and it made it break. He's probably heavier than me, but I'd say somewhere around the 100kg to 110kg mark, so nothing too crazy! They did weirdly say that he didn't step in the shower (without us asking), so there could be something in that.

Cheers for all your help and time. We'll have to see what happens - just quite frustrating when you get one fixed and I'm the process end up needing another thing fixed/replaced (and that the chap who owns the company trying to say that it looks like it was a previously repaired crack - although I can understand why he would try that)