Maharashtra Natural Gas [MNGL] — pipe lpg connection

Address: C7-201, KUNAL ICON COOPERATIVE HOUSING SOCIETY, Pimple Saudagar, Kunal Icon Road, Pune, Maharashtra, 411027

This is related to my complaint to mngl about discrepancy in billing amount. Their way of operations is very non-transparent. They keep sending reminders about bill pending upto rs.4k wherein when we reach out to them the amount pending seems to be rs.1548 only. I've made below payments to them in last 10 months:
Rs.670 paid on 21 march 2019 receipt0077555
Rs.925 paid on 27 apr 2019 receipt0107608
Rs. 868 paid on 1st july 2019 receipt 0157167
Rs. 925 paid on 26 oct 2019 recepit0269935
Rs. 1658 paid on 30 nov 2019 receipt0319362
When i go to their online payment link it again shows 1548 pending that makes it them making me pay rs.5046 and adding another 1548 which was pending on 31 dec.

They cannot confirm that they received receipt0077555 and receipt0107608 while amount was paid on their website with them sending me a text message with confirmation of payment. Multiple follow ups didn't help. Their bill amount is highly inaccurate and customer care is never reachable. Please help.