Tamil Nadu Electricity Board [TNEB] — overcharging of eb bill

My service no is[protected] name: p nagaraj residing at no. 6 kandan kollai, tirur post, tiruvallur dist - 602025. As per my eb meter reading i have consumed only 480 units during the month of july & august 2018. But the bill is raised for 600 units based on the last month consumption. This is incorrect. Why i should pay for extra 120 units which i have not consumed. This is costing me dearly for no fault of mine. The tariff changes when the reading crosses 500 units.in this case i am over charged and losing more money if i pay now. Please issue amendment to the meter reading immediately.