Omson Developers: Hidden charges after OC? Anyone else?

Omson Developers Pvt. Ltd Sector 126 mein is a total headache! OC milne ke baad bhi, they're hitting us with random "maintenance" charges. Almost 50k extra. I'm already paying a hefty EMI. The brochure mein kuch aur tha. Anyone else facing this? Is this normal? Should I just pay or fight it? I'm thinking of filing a complaint. What's the best way to deal with these chor builders, honestly?