After Possession no proper electricity supply in society

Can anyone please advice on my issue, I am staying in residential society where builder has given possession 1 year back however till today he has not provided us Urban feeder electricity supply, our area comes under urban zone still electricity which comes in our society is of rural feeder. Main light supply from rural feeder is only comes around 10-12 hours in a day rest electricity we have to born on DG power back, cost for power back up is Rs 16/- per unit which is 2.6 x higher than normal rate of Rs. 6.25 on main light. I think its duty of builder to provide basic facility like electricity before offering the possession now when its been more than year we thought not to pay DG charges as per 16 and want to fight with builder that we will pay 6.25 normal rate till proper feeder electricity will not be in place. We stopped this from last 3 months builder is sending our accumulated bills with interest @ 1.5% per month, can you please advice what can be the legal complications in this situation and how can we ask for our right. Even we are paying full maintenance changes as well. Regards Navdeep Kumar