Regarding boundary wall construction

Sir We are staying in an area where the land is sloping gradually. i.e,on one side houses are in higher level other side in a lower level The land on the rear side of our property is at a height of 1.5m and length 23.5m Now the builder who bought this land is going to construct a house and he told us he will construct a rubbled wall retainment for the land and a hollow bricks on the top and we demanded for Rcc because previously there was a rubble wall of the previous owner which collapsed into our property 5 years back due to push of the land and a legal case was going on for the reconstruction of the same using Rcc and he got fed up of going to court he sold the property to this builder and the case is withdrawn as this builder promised us he will construct an Rcc wall there. Later he told us that land is only 1.5m high and he is not going to fill it with sand to level out the sloping land and he's going to construct a house according to the present lay out of the landa,so there is no need of an Rcc wall and if you are so adamant you can construct by your own. As we are financially tight now we thought anyway he is not going to fill it so let him do it. Now the work is in progress The problem is that we felt that the construction is not up to the standards and he has increased the height of the rubble work from 1.5m to 2.5m and is going to fill it also and we asked him to stop the construction he is continuing with it to finish it quickly We are afraid whether this wall will collapse as before and what precautions to take Also he is constructing another house in the same plot a small part of it is in our region which is constructed close to our wall which is hardly 1m from our boundary If he is going to construct the second house also in the same way so definitely the filling of land plus the closeness of the house to the wall cause problems in the future Also we don't have the survey number of this new party (have previous owners survey number) Kindly help us to how to handle this situation so that he can't fill the land and to construct the house away from the wall Also is there anyway to recontinue the case as it is mutually settled Thank you Noreen