I wonder if any people here can help me with two queries.

Recently, my elderly mother was approached by a neighbour, who intends to build an extension to his house.   According to what she later told me, he asked if he could cut some branches from a Rowan (Mountain Ash) tree which were overhanging his garden, as I believe he is legally entitled to do. She agreed, and these branches (only) were cut, about a month ago. However, on returning yesterday from a week away with relatives, she discovered that every other branch had also been cut, and the wood/foliage simply left piled, where it had fallen, in her garden. There is not a leaf left on the tree, what's left of it anyway.   

My queries are these; first, will the tree now die? Secondly, can someone just get away with this, or is there any way in which he can be compelled to make some form of restitution, such as removing the remainder of the bole and planting a replacement sapling?   I should add that my mother is now most apprehensive about this neighbour's actions and attitude. She lives in Scotland, incidentally.