Smash up all the walls!
Luckily they plaster them up again afterwards.
This is what needs to be done when the damp rises and vexes you, as I was vexed previously. Now I pay, but I’m getting value for money. They leave some funky, trip-inducing chemicals in the walls. The fumes are marvellous.
The Waffle Group 
So, the big question is – was Hammer OS installed onto your walls?
I cannot believe I didn’t think of that.
Perhaps it’s because they used the chisel drivers, which are non-standard and unsupported.
ChiselOS is experimental?!? But I’ve been running it on my grouting for years!