dispute of flat

i have a allotment letter of 'A' catagery flat in Nirwayana society in sec-49 i submit 2 instalments 1st 12200 on 1992 or 2nd 46100 on 1998 .They r nt giving any responce even nt answering of my letters number of time i send to them letters but they nt responce or they r saying u r nt member of our society .i also apply in RTA for my current status . society members saying u take ur money without interest or with 10% diduction .what should i do please sir guide me its humble request to u