Ouch, Sorry to hear, I too had to read ya post several times before it sunk in.:mad2::mad2:
Its typical of the way this country is heading, personally I would send the boys around, but this scumbag sounds like he knows exactly what he is doing, so ya gotta tread careful & as mentioned by others, from a distance.
The missus read it too & she was gobsmacked too she said same as Pebbs suggested, send final invoice registered post.
Hopefully will get sorted.
As for ya so-called mate, he'd be getting a clip big style.
Good luck with it marra