Mahagun's extra charges before possession caught me off guard

My POA holder just got the final payment demand for my 2BHK in Noida Extension, and I'm honestly shocked. Mahagun, I'm looking at you. They quoted ₹78L for a unit in Sector 150, but now asking extra PLC and EDC charges never clearly mentioned. It's almost ₹5L extra! Customer support se baat karna bhi impossible ho gaya hai. Is this normal for Mahagun or other builders like ATS/Godrej? I'm based in Dubai, can't visit. What did others do about hidden charges just before possession?