Encroachment of neighbour in common space left for Light and vent

Hi Sir, In 2009 we constructed a two story house. At the time of marking rear neighbour requested to leave 1 & 1/2 feet of land vacant for "Light and ventilation" by promising that he will also leave 1 & 1/2 feet when he construct the house. We agreed and left the said space. In 2013 neighbour sold his land to some one else. Beginning of this year the new land owner started the construction of house, that time he told he will leave 2 & 1/2 feet of land and make a boundary wall. We agreed for that. Last month he constructed 2 Toilets in that 2 & 1/2 feet boundry and using our left space for Light and Ventilation. For this we objected and told neighbour that he has to remove these toilets or close the boundry upto roof. Neighbour was adamant that he is constructing these toilets in his land and don't want to listen any things. Now neighbour constructed toilets in adjecent to our space and using our space for Light and Ventilation by installing grill. We want neighbour to close the compound wall or demolish the toilets. What options we have and what actions we can take.