rainwater soakaway legal shared

Hi There, Our neighbours adjoined wall on a semi-detached property, just had their loft conversion done. They ‘didn’t want’ a downpipe on their side as it would ‘ruin the look’ of their half... Now the whole of their new flat roof along the house flows into our gutter and our down pipe and...

I'd appreciate guidance or opinions on this (potential) problem... When we had building work carried out on our property recently, we were surprised to discover that one neighbouring property shared a rainwater soakaway with us. This shared soakaway was in the rear garden of our property and...