250 f**k**g quid for a new box! What in the name of good f**k is it made of- gold! You can get cheap boxes online or someone on Facebook selling them. Them f**k**s are at it. I'd be telling them to go fcuk TBH. It's not like you broke it. If your working inside their house, it's they're job to remove the box so doesn't get dust in it. I wouldn't care about a bad review like that. Sure if you can explain your side, then people will understand. It's only dust. Go round there and take it apart, clear the dust, screw back up and job done.
As for the people pissing down your leg, that's something my granny would do. Only thered be no new box bought. Shed just be rubbing her hands that she got few quid of ya. Sounds like they are exactly like her lol