Rot in Bathroom

Hoping someone can advise.
We are having issues with our en-suite. It started over a year ago. Water coming down through the ceiling. Had plumber out who reckoned shower seal was gone and to fix it. We did. Its doesn't happen all the time but occasionally the ceiling is damp in the living room. Had a second plumber out and insurance guy. Both basically said unless we wanted to rip out the bathroom its hard to know whats causing the problem.

Roll on to now. I had noticed the skirting board that runs along the shower was chipping. Today when I was hovering the hoover head literally broke through the skirting board and its totally rotten. The floor tile right there looked loose so I lifted it and it came up so easily. Rotten there too. I looked in as far as I could and all the board and behind is rotten.

I am unsure what to do next? Im worried this rot has travelled and its worse that what it looks now, at that it looks bad. But is this an insurance issue?? do we need to rip up all the tiles, out the shower etc?

A difficult thing to advise on. The rot might not be as bad as it seems but you will have to find out the source of the leak. You could consider removing the ceiling plaster board below which would be easier and cheaper that taking the tiles apart. The leak is usually an easy fix but the cost is in gaining access. It might be an insurance job. Also you must establish if the leak is in the wall or below the tray.