Mahanagar Gas — Sept'21 bill reflected in Nov'21 bill with penalty despite having paid before due date ( screen shot attached )

Address:

Mumbai, India

I had paid my MGL Sept'21 bill before due date on 24th Sept'21, Plz view screenshot.
However, when I received my Nov21 bill, I found that Sept bill of Rs1260 had been added to it alongwith penalty of Rs127.
Since 15th Nov'21, I have been calling their Customercare requesting them to check and send me the correct bill, nothing has yet been done !!
I have been writing to [protected]@mahanagargas.com, and, [protected]@mahanagargas.com EVERYDAY enclosing the screenshot of the paytm successful payment, and, Xerox of passbook relevant page where the aforesaid amount has been deducted.
NO Respinse !!
I am a senior Citizen and it's causing me mental harassment for their inaction !!
Kindly help and oblige.
Thanks & Regards,
N C Pathak,

BP [protected],
CA No.[protected]