Why dont you use an exchange to encash? With an exchange there is no limit on how much you can encash. Your trading volume is currenlty low but am sure it will increase as time goes by. Try https://www.igot.com/?inviter_code=0862302642. They are a great exchange and also offer good price.They accept NEFT transaction and one of their bank branch is in Kolkata if that gives you more solace.