Mescom — charging of interest on bill for no fault of mine

Meter no klpr2218
I am an ecs user since several years.
My bill for oct nov dec 2017 was debited to my a/c in the month of dec 2017 with interest after several phone calls to your klpr office. I am maintaining sufficient balance in my a/c. Every month i reminded over phone about non debiting of the bill.in december i was informed that the claim was returned by bank that my a/c no. Was not correct and i was asked to give correct a/c no. I wonder, all these years the bill was paid through the same a/c and the number become wrong? The meter reader in january was telling me in loud noise that i may not have sufficient balance in my a/c. This i informed to your office and collect the dues without any penalty. They have agreed also. But now i was informed that they have collected the amount with interest (Rupees 77.00). The mistake was yours and i shouldn't be penalised. Hence pl arrange to rectify immediately