Tamil Nadu Electricity Board [TNEB] — Monthly EB bill - Average shortfall included

Address:

3/13B, Vembuliamman Koil Street,, Sathiyamoorthi Nagar, Thiruvancherri

I have been raised consumed unit of 140 for the month of JAN'22-feb'22 and the bill amount was 80Rs. now i tired to pay the amount in usual practise in TANGEDCO portal but here it is showing as rs.884 to be paid ( CC 80rs + average short fall Rs. 804) i dont know what is this average short fall?
8months before only there was an mfg issue in energy meter and replaced with the cost of rs.6000 from my side. i dont know why this much charges and why there is no prior notifications and justifications are provided?
even iam not afford to pay this.