My neighbour has in principle agreed to add a downpipe, although he hasn't yet acknowledged that the gutters will also need to be repositioned with the correct fall.
My neighbour's extension has gutters but no downpipe, hence the rain just sits in the gutter and then overflows onto my adjoining garage. This appears to be by deliberate design.
The neighbour's roof, gutters and fascias were renewed last spring. My neighbour says the contractor just copied...