Calculation of court fees in case of property dispute

I am Ravi. My mother has a House . In 1999 She Executed a Settlement in favour of her four Sons ( me and my three brothers). On the same year we four brothers executed a Power of attorney in favour of our mother to stay in the house for her life time and we also include the line “No one has the right to cancel the power of attorney”. Because of that above line , Officials in Registration Department assumed that the document as SaleDeed , After two years one official of Registration Department , asked one of my brother to pay extra amount. That person without asking anything unknowingly pay the asked amount. Our mother expired in 2016 , after that we saw Encoumerence Certificate , that power of attorney document entry was comes as Sale Deed . To Cancel the above entry through Court Order, How the Court Fees is Calculated , 1. On the current market value or 2. On the date of execution of Power of Attorney.