The neighbouring small resort iis a jerry built Thai affair where noone thought to put land drainage in.
Since we landsaped and put up a dividing wall the water has been building like a dam on their land.
When I was putting my own land drainage in a few years ago I asked them if they wanted to run drainage through it in return for a small contribution to costs - they refused.
So now it seems they've simply either punched a hole through under the wall which has caused a mall area behind one of my drains to subside as the torrent finds its way into my over drains.
I can of course just pour concrete and dam it up again, if he (piss head tatooed Brit) wants to pay for the rectification plus 10% of the cost of my drainage I'm happy to let him hook up - otherwise he's just pissing me off.
Suggestions?