Tamil Nadu Electricity Board [TNEB] — excess billing while out of station

We belong to tirupur, our consumer no is[protected]..we are out of station for the past two months but we got a bill.amounting 500 units...you can check it out in online history.Till date our reading shows around 2950 units but the total units consumed given in online history sums upto 3300 units..we can easily find out that the last taken reading is 400 more units than actually consumed...kindly take steps soon since we have only a week left to pay the bill...