Grandfathers property mishandled by executor.

After her death my grandfather had a promoter demolish his mothers house, which he had bought in her name and in place of that house he had the promoter erect three interlinked apartment buildings of 4 floors each, the property was approximately 11 cottah and 8 chattacks. My grandfather had four brothers, and after the building was constructed he allowed his four younger brothers to choose their apartments first, afterwards he was left with two apartments on the fourth floor of the third building. The promoter died before the could handover the possession certificate of the two flats to my grandfather, my grandfather himself died two years later in 2007, he had left a will, which stated that me and my cousin sister were joint owners of all his property including the apartment in question in Baranagar. My cousin sister's mother my aunt was the executor of the estate, after probate was granted she did not lock the flats and that in turn allowed one of my grandfather's nephews to illegally sell my sisters flat and rent out my flat, it should also be noted that he works in the customs department of the West Bengal government. When I confronted my aunt, she said she could do nothing about this situation personally but was trying to solve it through legal and political means, when I spoke to the nephew he said thatmy grandfather had no property and that it was still in my grandfather's mother's name. Whenever I have tried to do anything regarding this issue, my aunt has been uncooperative. I need my flat sold so that I may pursue my education abroad. My aunt has consistently lied about trying to solve the problem and that has led to 2 years of my student life being wasted. Please help me, I desperately need the flat sold.