Hidden trouble after getting possession without OC

Possession toh March mein mil gaya tha Mohali ke Godrej project mein, but abhi tak OC nahi aaya. Builder ne bola tha sab clear hai, par ab pata chal raha OC ke bina kitne issues hain. Society formation bhi atka hua hai because of this. Builder-buyer agreement mein bhi OC ka clause itna vague tha, tab dhyan nahi diya. EMI chal rahi hai, property tax bhi higher lag raha hai. Builder ka response bhi zero hai. Kya RERA mein complaint karna worth it hai for delayed OC? Ya OC ke liye wait karna hi solution hai? Kisi ne same situation face ki hai kya Chandigarh mein, especially Sector 49 ya Mohali mein?