Calcutta Electric Supply Corporation [CESC] — Irregularity in meter reading and miscalculation o[censored]nit consumed and excess bill

Please refer to
Bill No.[protected]/05210, bill date: 15/6/21
Bill for May, 2021
Customer ID: [protected]
As per my electricity bill, there is nothing written in previous reading but present meter reading is 4148. It is written that unit consumed is 136 Unit. Please clarify your calculation of 136 Unit.
My connection is more than 11years and my consumption of electricity is very less as we do not have electrical gadgets like Refrigerator, Television, washing machine, mixer etc.
The average unit consumption is less than 40 Units. Last month( April, 21), I paid Rs.170.Bill for month March, 21 was 19 Units and Rs.190. Bill for Feb, 21 was Rs200 (25 Units)
So, Bill in the month of May, 21 how I have consumed 136 Units?
Please do the needful.