We have almost finished building our house, our neighbour has just moved in yesterday. Their builder installed their retaining wall which upon completion several weeks ago. We contacted their builder and voiced politely our concerns about the lack of height and the builder said he would go and look at it. I assume he had workers do the wall for him and he had not seen it. We heard nothing from the builder again - nothing happened with the retaining wall until a few days ago when the fencer turned up to install the fence which we had verbally agreed to share the costs. However they were organising the fencer as the wall needed to be completed first. Upon speaking with the fencer, he also was not impressed with the height of the wall (i.e. there was easily another foot of soil above the height they did the wall to). The fencer was told by their builder to install the fence the wall was not changing. We are still intending to install underlay, grass and top dress our side of the fence and cannot level off to the level of the wall (why do we have to change our property because of their errors) as it will be below our buildings brick level. Any idea what we can do about this legally under property law? They did cut into the ground a long way - i.e. our ground level is almost at the bottom of their window sills.