Prasad — Municipal tax - unauthorized construction penalty

Address: Rangareddy, Andhra Pradesh, 500018

I have purchased new flat as per the new house approved go. Builder deviated relates to set backs and he paid penalty around 20 lakhs and got the occupancy certificate from GHMC. All the flat owners received property tax notice and in that they mentioned some amount as "unauthorized construction penalty". Why should we pay this amount? For your info I have attached the occupancy certificate and pt demand