Sunder Homes: My 3BHK upgrade and surprise charges

After 5 years in my 2BHK, upgrading feels like a trap. Sunder Homes in Sector 70A just added huge 'utility connection' and 'IFMS' charges at possession. Not in the brochure! Is this common in Gurgaon? What hidden costs did you face? How to fight these last-minute demands?