Siddhartha Vihar 3BHK: My post-possession cost shocker

Moved into my 3BHK in Siddhartha Vihar just two months back, possession was in March. Honestly, the final 'all-in cost' was so different from what Almighty Developers quoted initially. Stamp duty, registration, then suddenly some 'meter installation charges' and a hefty 6-month advance maintenance fee nobody mentioned upfront. It felt like a constant stream of extra payments. My budget was around ₹78L for the 3BHK, but with all these hidden charges, it went up by almost 8-10% more. I wonder if negotiation on these things is even possible. For example, in Shalimar Garden, can you really push back on these extra charges or are they fixed? Has anyone else faced this post-possession shocker in Ghaziabad? Did you manage to negotiate any of these 'hidden' costs down, ya fir sabko pay karna pada? Feel like I missed some critical questions during the buying process.