Uphill neighbours extension and downpipe into ground has damaged and continues to flood my propert

sttiv

My uphill neighbour fitted a gutter and downpipe where there was not one previously  on his property and fitted no drainage for it so the water goes  straight in to the ground. It drains down my garage wall and underneath my garage to flood my paths. He also built a substantial extension which has compounded the water drainage problem. Additionally, his garden wall runs downhill but the sweep holes are blocked so all the water from further uphill runs along the inside of his wall until it is blocked by a wall between our properties. This wall fell under the pressure of  water and torrents of rain water now  pour from his property and flood mine. My property is now showing signs of subsidence,  there is a smell of damp in one room and I think it's all due to this excess water.  The neighbour denies any responsibility but I've Iived in the house 40 years and never experienced any water issues until the neighbout made these changes. The council, water authority and insurance company seem unable to help but the problem is getting worse and I'm having to pay for the fallen wall  (not on my deeds) to be rebuilt and to withstand the water pressure it will be under and with weep holes that will still direct water in to my property. Can you advise what I should do as I fear what damage is being caused around and beneath my property that I cant see.  Thank you to anyone who might have suggestions. Sttiv.

ashe

Surely building control sign off would cover the drainage?

sttiv

My checks have established there is no regulation about drainage going streight in to the ground. I didn't think about building control so will have a go at finding out what they signed off .... thanks 👍

sttiv

My checks have established there is no regulation about drainage going streight in to the ground. I didn't think about building control so will have a go at finding out what they signed off .... thanks 👍