Tamil Nadu Electricity Board [TNEB] — High bill value

Hi team I have made my payments on regular basis during Covid lockdown as well but reading was only taken last month and now they want us to pay Rs 21401 for September usually we get an amount of rs 3 k to 6 k and units between 1000 plus to 2000 plus but for last month the unit is 3410 which is way high for 1 floor we have 3 floors and one commercial line but for one floor this is way high
Please help