Reliance Energy — after paying previous month's bill, the same is reflecting in current bill

Account no.[protected], bill for march is paid 2830 on 20 th march2018 at 12.54pm.

Bill generated for april 2018 is showing rs. 6260 as outstanding bill.
When already bill is paid for previous month as on 20 th march2018, why the the bill is generated inclusive of two months bill?. Even we can not pay current bill month amount online.
After contacting customer care, they say pay only for current month. How one can pay partial amount of bill online?
Please rectify the bill & regenerate it for further communication