how to get rents of child property

I am divorced with my husband in 2016apr, my x husband has registered a house on my son as part of divorce settlement, however as my son is minor , his father and myself are written as guardian 1 and 2, but my x husband n his mother are staying in that house still and they are not paying a single rupee since my son born and even after divorce, there is a pre mutual written paper by him saying that he pays my son's bills but he dint pay anything so far, I am now unable to go for work due to illness and I am eagerly looking for financial help for my child. please suggest how to take this ahead.